cometaryorbit

Re speed: the advantage F-Steel would give would be reaction time, not necessarily outright speed. Windrunner flight is incredibly fast with enough Stormlight (they can run ahead of a highstorm, which is 390mph, or about 40% of the speed of sound). Marasi with the Bands is faster than that, but the Bands may be a special case. No one else we've seen use F-Steel goes anywhere near that fast. Even Bleeder in SoS I don't think needs to be over 100mph to do what she does. Wax can chase her and Allomantic flight is likely nore like 60-80mph. TLR might be similar ('far faster than a full pewter flare' but not a blur, and definitely no sonic boom). I think pewter speed is beyond human, but also mostly irrelevant for Elend and Vin, because Steeljumping is faster. Vin says twice as fast as a galloping horse in TFE, so 60-80mph - I doubt Era 1 horses are as specialized for speed as our modern racehorses, so probably more like 60mph. But that's still probably twice as fast as her pewter speed. Roshar is vastly higher Investiture than Scadrial. I don't think a Fullborn can remotely operate on that level, short of Bands of Mourning leaking-mist stuff (even TLR doesn't leak mist). And the Bands are *still* less Invested than a Shardblade. So I'm skeptical of Leeching being *practical* against a Radiant. It would work on Rosharan Investiture, sure, but what seems instant against a few flakes of metal in Wax's stomach might be too long to be relevant for a fight (or take an impractical-to-swallow amount of chromium) against a Radiant full of Light.

During the Desolations, the losing-their-minds possibility wasn't known: that was a total surprise at the time of the Recreance. I was talking about the ancient Desolations, not the current True Desolation.

One caveat: we don't really know what a few of the Feruchemical abilities actually do. Does Identity do anything other than let other Feruchemists use your metalminds? What does Feruchemical Fortune do exactly? What does Feruchemical Investiture do outside of SoScad Medallions? (That one is really important to the question of overall power level, as it determines how much they can boost their Allomantic strength). Strengths They're incredibly powerful - one of the, if not the, most powerful non-Shardic beings in the Cosmere*. Mistborn are already very powerful - ridiculously so against people using metal weapons or armor, but Kelsier beat six hazekillers and Vin (admittedly unusually skilled and strong) dealt with ten without needing atium. Adding atium and/or duralumin makes them way stronger (though duralumin is dangerous since it leaves them without metals until they drink another vial). Duralumin + Soothing/Rioting means control of koloss (and possibly kandra, though Harmony might not let that work in Era 2). Iron/Steel are obviously powerful, but Pewter Allomancy is often underrated, IMO - the strength boost isn't huge (about x2 for normal burn or x3 for flaring), but it does so much more than just muscle strength - speed, grace/dexterity, physical toughness and resistance. And Compounding covers up Mistborn's most important weaknesses - the limited "peak" on flaring, and their lack of (combat) healing. Flaring Pewter only makes you so strong, and while Duralumin Allomancy can raise that limit, it's dangerous and not very controllable - F-Pewter is much better for that. A-Pewter only helps with healing on a "medical recovery" time scale, and while it also toughens the body to help against e.g. breaking bones, a cut throat is still lethal. But not with F-Gold. The most impressive Compounding powers are probably Atium (though only really available in Era 1, except for Marsh), Gold, and Steel, though Pewter and Zinc are also super impressive. Bronze Compounding (never need to sleep) is also pretty cool. F-Gold + F-Steel is probably near invincibility, and combining that with A-Atium is just unfair. Add in F-Pewter for one-hit-kill strikes... Even without access to atium (say in Era 2) Zinc Compounding to process the shadows of A-Electrum might be nearly as good. Weaknesses But, there are limits... 1) Availability of metal. Generally, not all the metals are available. In Era 1, they have atium (and potentially malatium - TLR knew of it - not that it's terribly useful) but chromium/nicrosil and cadmium/bendalloy aren't available. (TLR presumably knew they existed, but the Final Empire didn't have the technology to make them.) So you either get the near-invincibility of A-Atium and the near-endless youth of Atium Compounding, or Leeching and time bubbles, but not both. 2) F-Gold healing needs metalminds on the body to work. Therefore, it presumably can't save even a Compounder from anything that melts away/vaporizes the metalminds, or blows the body apart sufficiently that the metalminds are no longer attached to the largest piece of body. In Era 1, or even AoL times, with relatively limited power weapons, it's effectively true invulnerability (Miles survives dynamite he's holding trivially). But as technology advances, that should change. 3) The amount of power a Fullborn has is limited to how much metal they can fit in their stomach (to burn) or how much power fits in their metalminds (Feruchemically). They don't actually have infinite attributes - they can't become a black hole with infinite weight, or travel at the speed of light with infinite speed, etc. And Feruchemy has diminishing returns at high rates of tapping, so it's likely that the limits are a lot more sane than they appear at first glance. Wax can use months of weight to become "heavier than a building", but I doubt even a Fullborn with several pounds of completely full by Compounding ironminds could become as heavy as a mountain. 4) Leeching still works. And with a primer cube, Leeching can be an area effect... 5) Aluminum is still a problem. A Fullborn still can't Riot/Soothe through an aluminum hat or Push/Pull on aluminum. Even A-Atium won't save a Fullborn from aluminum bullets (aluminum doesn't have an atium shadow). F-Gold healing won't get an aluminum bullet out of them (it will presumably keep them from outright dying, but staying alive with bullets in vital organs is probably going to burn health at a horrific rate). *at least, in a "who would likely win in a fight" sense. There are others who have more versatility, or more sheer quantity of Investiture. (Cosmere general) Definitely (although I think 2-3 times is pretty low end, but yeah, Marasi with the Bands is super extreme even for Compounding. We see TLR use Steel Speed and he doesn't go anywhere near that fast.) We don't know enough about Unsealed Metalmind creation to assume that being Fullborn is enough to do it - there may be "mechanical" or "technological" components, or it might have needed Kelsier's Sliver expanded mind to design the process (kind of like designing Hemalurgic constructs).

I figured Sazed was storing down to very low weight, to the point where his clothes and bracers/rings were a significant part of his weight if not the majority of it. I don't think storing down to 15kg is extreme at all - I see no reason why he wouldn't store (say) 98% of his weight - leaving him at maybe 2kg of his own weight + 2-3kg of clothes and metalminds = 4-5 kg total.

Yeah. i think there's a key difference between "the only reason I had left to live" and "the only reason I had to live". She's not saying that being with Elend is her only purpose in life. It's more that through HOA, the world is ending, everything is falling apart and dying. Vin has already, at this point, essentially left her "earthly" life by Ascending (as Preservation, she's certainly not dead, but she's not really human anymore either). Elend is really her only link left to human life. Her "meaning of love" line in SH does make it sound a bit more problematic, but I think it's still key that she's basically left (mortal/human) life behind already before she sacrificed herself. She could have become a Cognitive Shadow, sure, but... Vin has really kind of been... weaponized by both Ruin and Preservation for her whole life. She never really had a chance at a normal life.

Nah, g forces will incapacitate someone due to weight way before they do real damage. Wax's Push strength is just as high when he weighs 18 pounds as when he weighs 180. So if he's launching at 2 g normally, he can do 20 at low weight - with the same Push strength! And maybe 200+ with duralumin (though he'd need duralumin pewter to survive that one). Mistborn + Feruchemical iron has vastly, vastly higher mobility than just a Mistborn. (I do think Push strength is generally higher than you're assuming. "Continuous" Pushes are often actually quick on-and-off, I think. 3 g for Vin seems very low; she weighs 100lb at most and is an unusually strong Allomancer. I think Kelsier's jumps are well beyond what say 250lb of force would do for a man his size. He's pretty tall.) Wax's body can take 15 g in a brief burst, sure. Even without pewter... briefly taking 15 gs (we're talking bursts less than a second) is possible for a perfectly normal human. Human g-force tolerance in short bursts is a lot higher than generally assumed. (42 g for 0.9 seconds has actually been done, but while there was no permanent damage, there were temporary effects significant enough to really mess up a fight, e.g. burst blood vessels in the eyes.) Shardplate isn't *that* tough. Kaladin may well have used 10 Lashings there - it's totally possible, I'm only arguing that really highly stacked Lashings are generally not used for flight for practical reasons, not that it's beyond Windrunner abilities in theory- but hammers and such can crack it. -- OK, but "several hours"? There aren't enough Fused in existence to make a fight against 100 4th ideal Radiants last that long, IMO. -- That's why the really smart strategy would be to put all humans in or very near the 10 Oathgate cities, using Soulcasting for waste disposal etc. Then the Fused can't get at humans without dealing with Radiants. Sure the Fused respawn, but they need singer volunteers for that. How many horribly one sided defeats in a row before the Singers just give up seeing these punching bags as gods? In that setup, you won't get many Radiant losses at all. They have Plate plus their own healing plus backup from other Radiants with Regrowth. --- Well I think density is power here - a person can only hold so much Stormlight (Szeth says he's at the limit a couple times). Liquid Investiture is really strong. And if there isn't a specific difference, I think it's because it's "purified" Dor so almost generic Investiture- Well of Ascension liquid doesn't do the same thing as Mist, so state can matter even for the same type of Investiture. Yeah, Thunderclasts are more siege weapons. They're great at that, but how is one going to actually kill a Radiant with mobility powers + enough healing that one hit isn't fatal? and over half the Orders have mobility powers (Gravitation, Abrasion, or Transportation).

That would be super weird, because metal oxides are not really metals anywhere else in the Metallic Arts.

1) I was thinking that the "maybe 1" absolutely required Steelpushing, but the 2-3 might not. I don't think the Roseite case is relevant here because liquid Investiture was involved and that's crazy powerful. But yeah, aluminum armor piercing would be very poor (unless the "crack or explode rather than puncture" nature of Shardplate failure means energy is more relevant than momentum). 3) I don't think Stormlight will help all that much with g-forces. The healing will certainly prevent lasting damage, but Kaladin (or any human) will be unable to fight effectively at much lower g levels than those that would do lasting damage anyway. As for short bursts, I don't think either character is getting to accelerations that would be that devastating (short of duralumin-steel, in which case duralumin-pewter can help deal with it). It's not just about speed, it's about maneuverability. I agree that a Windrunner with sufficient Stormlight is faster *on a long, straight flight* than any Mistborn - a lot faster (highstorms are at ~370mph and Kaladin's flown with them). But I think a Mistborn with enough coins/horseshoes/whatever can *turn and maneuver* faster - or at least that their flight style as we've seen it is better at fast turns and maneuvers than what we've seen of Windrunner flight (which admittedly may be less mature technique than Steeljumping). And a Mistborn with f-Iron is *definitely* more maneuverable. Wax at low weight can take 15 g's *and weigh the same as he normally does*. So he could fight just fine at 20 g whereas Kaladin couldn't move his arms. With low weight and pewter strengthening he could endure ridiculously high accelerations (hundreds of g's). 6) It's more "why are normal soldiers in the major battles either". Holding ground, sure, but I don't think every Fused in existence plus a thousand Thunderclasts could beat 50 Windrunners backed up by say 10 each Skybreakers, Dustbringers, Elsecallers, and Edgedancers - all 4th ideal - if they had enough Light. Without Anti-Light (which didn't exist yet), what can the Fused do effectively against a flying Radiant in Plate with a Blade? One hit to the gemheart kills the Fused, while the Radiant is shrugging off otherwise deadly hits left to right.

Yeah, they probably didn't control HoA level huge numbers of them. Against bandits and "wasted men" tribes a few hundred koloss operating under central control would be pretty overwhelming. I wonder how many koloss there actually were in TLR's time? Ruin apparently increased their numbers a lot, so I don't think it was as much as the 300k (is that correct?) at end of HoA. But Jastes already has 20k in WoA, and while they were already replenishing their numbers with reused spikes I don't think they were increasing them (without Ruin free they probably couldn't make more spikes). And I doubt that Jastes had a majority of all the koloss in existence. So maybe something like 60-120k?

Yeah I think Iridescent Tones refers to a harmony (heh) of color and sound. The whole gaseous Investiture thing is really weird, because Breath is very different from Light is very different from Mist (and Mist, at least, isn't actually *gaseous* - it seems basically Physically identical to real water mist, even leaving water behind on the ground, and mist is a suspension of tiny liquid droplets, not a gas). I wonder if Cultivation on Scadrial would create a green Mist and Harmony on Roshar would create a uniformly white Light? But it may be even weirder than just strictly being planet-dependent, because there is a green Lifelight Mist in the Nightwatcher's Valley.

While I don't really disagree overall (Kaladin is hugely favored to win), I do have comments or questions on a few of the details... (I added bracketed numbers to your quote) 1. Hmm, good point. I don't think we know enough about breaking Plate to be sure*, but against RL armor (where momentum matters, not just energy) aluminum bullets would be vastly inferior to lead ones. In fact aluminum bullets would have real trouble against large animals or large koloss - aluminum is less than 3x denser than flesh, so it can only pierce so far. *It doesn't work exactly like piercing real world armor... it cracks or explodes, but doesn't get holes through it (or even deep dents, I don't think). 2. I agree. In fact, I don't think a Steelpush or Ironpull actually Invests the metal being Pushed/Pulled. The Investiture creates the force, but doesn't directly Invest the metal. Just like if an Elantrian creates a flamethrower blast of fire someone being burned by it isn't being Invested by the Dor. But even if I'm wrong about that, yes, the Investiture scale is totally different. Lashings work on people by default, which is way more Investiture resistance than Iron/Steel can handle without super exceptional strength. 3. OK, here I strongly disagree. Iron/Steel has the disadvantage of needing anchors, but Windrunners *do* feel g-forces (yeah, by RL physics they shouldn't, but they do). And Mistborn Wax has pewter Allomancy, so he can take a lot of g-force. Also, Steelpushes/Ironpulls tend to be short-burst (unlike Lashings) and the human body can take a lot more g-force in short bursts than over time. So I think he's actually likely to be less troubled by g-forces than a Windrunner. (Now, Kaladin won't crush himself because of Stormlight healing, but that doesn't mean he can function well enough to fight under high g-forces. Stormlight oxygenates him without need to breathe, but that won't give him the strength to move his limbs at high g. He'd have to constantly cancel Lashings and re-Lash to move at really high accelerations and still fight. I think there's a reason we don't generally see x10 or x20 Lashings used to fly.) 4. Yes, the duralumin emotional allomancy trick would only be workable as an opener before the fight really starts (assuming that 4th ideals don't have the Investiture resistance unless tbe Plate is summoned). I don't think it's really a fair tactic in this match up (as it would require Wax being given an unfair advantage to work, at least in knowledge of Kaladin - his being able to "shoot first" is probably 50/50). We don't know how strong Wax would be, but I'd argue that for a trained fighter like Wax even a second would be incredibly significant. It doesn't seem fair for this match-up to give him the level of training needed, though (given Vin with her super Allomancy intuition didn't get it in a year or more). Neither of these are likely to be decisive here. I thought they were worth mentioning, though, because while a Mistborn is at a crushing disadvantage in a direct physical fight against 4th+ ideals (and significant disadvantage against some, if not most, 3rd ideals) they do have some powers that are kind of outside the Radiants' sphere. 5. Dead Plate does heal with Stormlight, but not on a time frame usable in combat. And yeah, 4th+ ideals are just super hard to kill without "anti magic" weapons (anti-Investiture, Leeching/larkin/etc, suppressor fabrial, Nightblood ... even aluminum has trouble with Plate in the picture, and suppressors are less effective at 4th). I kind of wonder why the Heralds even were fighting in the late Desolations- they seem obsolete - but I guess if pre Honor death Bondsmiths couldn't do the Perpendicularity thing (maybe only grant Light by touch?) they'd have been much more vulnerable to running out.

Most of these are actually really hard questions... 1. This one slightly depends. If you can't get Stormlight off of Roshar, and don't get the Heralds' ability to directly draw on Honor, the Blades are only usable on Roshar. But it seems like it's at least not obvious how to use the Bands to Compound to recharge themselves, and maybe not possible. But if we're just considering the powers themselves, I'd have to go with the Honorblades, both because of Progression's healing not being limited to self like Gold Feruchemy, and because Soulcasting is ridiculously awesome. Another advantage of choosing the Honorblades is that the right five Honorblades grant all ten Surges, so I could give powers to up to five other people and still have all ten myself. 2. Full Feruchemist, Feruchemy just has so many everyday-life applications. 3. This one really depends, for a lot of reasons... - Which Shard? There's some (Ruin, Odium, likely Dominion if the Skaze/Fjordell are a fair representation of that Intent) that I'd never touch. Others (Cultivation, Preservation, possibly Invention depending on the exact meaning of that Intent) would fit me very well. - is the implication of the question that if I choose the Shard, I have to keep it forever, vs doing things with it then passing it on before Intent overwhelms me? - what is it that makes Elantrian immortality so difficult? So if choosing Shard implies remaining the Shard permanently (thus loss of self) or getting a random Shard, then definitely Elantrian. Though even that isn't super attractive, if it's that wearying and you don't really get active powers outside Arelon and its vicinity. Plus being immortal without everyone else in my life isn't that great. If I can choose which Shard and retain the ability to pass it on, then I'd do that. 4. Awakener, because being a Radiant means you have to stick to the oaths or your spren dies. But this one's slightly hard because 5th Heightening means lonely immortality. If I could have say 8-10k Breaths it would be easy. What I'd probably do is split up the Breaths anyway... Vivenna at 3rd Heightening (though I think well above minimum for that) is said to be in a position to barely age at all and essentially immune to disease, and even 1st extends life by about a decade. So I could give one other person 3rd Heightening (600), keep 3rd for myself (600), and still give four other people 2nd (200) or sixteen other people 1st (50). Or give ten people, including myself, 2nd.

Wouldn't aluminum bullets ignore reverse lashings? Wax's best move here is probably to lighten his weight and use steel/iron for mobility to stay out of Shardblade range, and rely on guns for offense. Pretty much how he'd do it for most of his career ... the new Mistborn powers are probably only relevant here to give him a little better mobility (steel/iron rather than just steel). He can't afford to get close enough to use chromium Leeching or pewter strength, and pewter dexterity/speed is less relevant if he's moving using iron/steel. The Mistborn powers would matter much more against a more "subtle" Order like a Lightweaver, where tin and bronze might be critical. A coppercloud might have some weird effect on spren, since they're Cognitive entities, but since Syl will be Physically manifested as a Shardblade/spear it shouldn't matter here. But he doesn't have much of a chance, because Shardplate will take several bullets to get through since Wax can't Steelpush on aluminum bullets to boost their force. And living Shardplate can heal itself, I think. 4th ideal Radiants are just really, really hard to kill. Though there are two possible wild cards: - a duralumin emotional allomancy blast, or maybe even regular flared, might effectively take Kaladin out of a fight... but it doesn't seem fair to assume Wax knows what emotions to choose to hit Kaladin's vulnerabilities. - electrum Allomancy is a capability that I don't think Radiants really have a good counter to, which could potentially make a Mistborn also incredibly hard to kill. But it seems like getting anything more useful than "counters atium" out of it takes serious work (Vin didn't get it despite her exceptional intuition with Allomancy) so Wax probably won't have this. So I don't think either of these would let Wax win, but they are IMO relevant to Mistborn vs Radiant fights.

Yeah I was really surprised to see that, but in hindsight it makes a lot of sense. Marsh does tell Vin in TFE that the two "high metals" - atium and gold - share a pulse pattern just like the four physical metals and the four mental metals. With the full Allomantic table, that means that atium had to share the temporal quadrant pulse pattern. That is really why I ended up liking the retcon - imo it actually fits better with the existence of Seers (they were really just electrum mistings) and the fact that a thousand years of Seekers didn't notice that atium's pulse was super weird. Because it wasn't - the atium they knew was really a temporal alloy. If it was decided around the time HoA was being finalized and the Allomantic table came out, I'm not sure its even really a retcon in the usual sense. Though if it was decided by 2008/09 I don't know what the old WoBs about "swapping out" atium/malatium mistings meant.

A Shard by itself has "only a vague will", Sazed says in the HoA epigraphs. It has drives or desire (Intent) - but not sapience/intelligence. More like a simple animal's drives - a fish isn't particularly smart, but it still has drives (hunger, fear, etc).

Yeah, all the people who survived (all five storage caverns) ended up in the same place (which became Elendel). The nobles continued to keep track of family lines.

I'm not sure, there is a line about Allomantic control explaining why Inquisitors were way more loyal than regular obligators. TLR might not have actively controlled them, but with his super Soothing he could, and the knowledge that it was possible would have kept them from rebelling (some Inquisitors controlled koloss under TLR, I think*, so they knew about Allomantic control of Hemalurgic creatures). I think Inquisitors would generally be super hard to control. They have more spikes than a koloss, but have full intelligence/will and presumably the ability to burn copper. *Since the Inquisitors didn't have duralumin (except possibly some former Mistborn), those probably would have been either former Mistborn Inquisitors or those with a double spike for one of the emotional powers. A default former-Seeker Inquisitor would have slightly weaker than base power level in zinc or brass due to Hemalurgic decay, so probably couldn't control koloss.

*Some* Cognitive effects other than blocking healing particular injuries are possible, but I do think it's pretty limited without other magic besides the healing. Miles saw himself as godlike, but he didn't heal into having superpowers. TLR not only saw himself as being godlike but had nearly everyone else in the world believing it too, but he still needed the atium compounding not to age. So at the very least, I don't think healing can just add/change arbitrary things. There might need to be a template/idea/Form of what you are becoming in the Spiritual Realm, or a Connection, or something. I'm not sure if self hypnosis would work. Depends if you can "trick" your own cognitive aspect or not. It can clearly change over time due to personal growth, but I think there's a philosophical question there - are you growing into something that you always had the potential to be? If so, there might be a limited set of possibilities that are "valid" for any particular individual, and only those possibilities would be accessible regardless of what tools (eg self-hypnosis) were used. Now, if you can directly change your Spiritual without relying on healing to work through the Cognitive, then I think almost anything becomes possible. Sazed/Harmony could fix "unhealable" injuries like Cett's legs or Terris eunuchs.

Maybe they're not really pewter. Maybe they're a lerasium-pewter alloy or atium-pewter alloy from TLR's experimentation. There were probably lerasium beads not accounted for. Maybe TLR took the others and experimented with them. I would tend to think that using a pewter spike on someone without Physical Feruchemy powers would not steal anything - there's no valid power to steal, so the spike would just make a mundane (presumably fatal) wound without affecting the spiritweb, and no charge would end up in the spike.

Well, there's a couple of cans of worms here. 1) In the HoA epigraphs, Sazed/Harmony specifically states that TLR's "essential Allomantic strength" is the same as the other Lerasium Mistborn. That WoB doesn't say TLR was stronger, it just says that he got his Allomancy through the Well rather than a bead. However, its possible that the same strength idea was retconned at the same time as the Well thing was established. But if the line is unchanged in the leatherbounds, then probably not. Can someone with a leatherbound HoA check? [Now, TLR would have been effectively stronger than Elend even with the same "essential" or base strength - due to experience/skill and near-savantism in the commonly used metals (and quite possibly actual savantism in brass since he seemed to have it on all the time, likely bronze too...) - even without reverse compounding.] 2) That WoB is very unclear. It's not even totally clear that "he" is TLR not Marsh, though probably. And "his most dramatic effects" - excluding moving the planet and reshaping the world with the Well - were plausibly creating koloss/kandra/Inquisitors and controlling vast numbers of koloss. TLR 'using' Hemalurgy doesn't have to mean TLR himself was spiked, it could mean creating Hemalurgic constructs.

Autonomy's tendency to work through avatars might be a way to deal with internal contradictions, or explore different meanings of Autonomy. I don't think Autonomy - at least as interpreted by Bavadin - is really either "maximizing her own free will" or "ensuring everyone has equal free will", though. It's more combative self-reliance. Moonlight says that under Autonomy people can generally live mostly unbothered, unless they try to advance, in which case it's super survival of the fittest. The Wax and Wayne copies talk about competing to be the best example of that role, a similar survival of the fittest concept. The Cycle also talks about proving himself by capturing Marasi. I think what Autonomy (as interpreted by Bavadin) wants to encourage in the world/universe is combative self-reliance: seeking or fighting for one's own independence or free will, but an free will that includes the possibility of imposing on others. That's inherently not a "freedom for everyone" concept*, it's a competition that some will lose. Autonomy probably thinks that freedom that isn't won isn't real freedom (if it's given to you by a higher power it's not *your* freedom, kind of concept). And perhaps that self-reliance needs harsh conditions/dangerous competition to develop. This isn't a "freedom as universal human right" concept. This is a "freedom is something you seize" concept. *Except maybe in a cold "everyone has the freedom to try, it's just that most will fail" sense. Sixth of the Dusk

I did list that as a possible reason for the Kaladin/Shallan healing difference- I think it's definitely a factor. However, I do think that Kaladin in RoW being near 4th ideal for some purposes (resisting suppressor etc) may also be relevant.

Hmmm, that wording is actually kind of odd: "The Voidlight inside the Fused wasn’t under pressure as it was in a gemstone, perhaps" That suggests the anti-voidlight in the dagger gemstone is annihilating with the Voidlight she's holding, not the Odium Investiture making up the Fused Cognitive Shadow itself. But then why does it permakill the Fused? I thought it was literally converting the Shadow's own component Investiture into energy...

I wonder if "Sibling" is used to avoid revealing their true name to humans.

That's possible, I guess, but I'd still call a massive explosion 'reacting in a significant way'. And unless Light and anti-Light are vastly less dense (by orders of magnitude) than any conventional gas*, what we see in RoW just can't be a stronger than matter-antimatter reaction. *which, hmmm, I guess is technically possible. There's no evidence Light is made of conventional protons-neutrons-electrons atoms, so each atom-equivalent might have a mass much less than a hydrogen atom. Maybe Light "atoms" are made of some kind of Investiture particle, or are Investiture-stabilized exotic atoms, or something. If the molar mass of Voidlight is say 0.001 (1/1000 hydrogen-1), and the amount of Light storage space in even a decent sized gem is very small (more like a cubic millimeter than a cubic centimeter, or less) it maybe could work. Then you'd get ~1.6 x 10^4 = 16,000 joules ... which is equivalent to a bit less than 4 grams of TNT, but if the energy was released spread out through the body of the Fused stabbed (Raboniel or her daughter) and/or took a second or two for the reaction to complete, wouldn't necessarily be explosive. Water takes up heat very effectively - specific heat of water is a bit more than 4 J / gram / degree C, so if the energy release is spread out a bit in time and/or space it wouldn't necessarily do anything dramatic to a human sized Fused body (if evenly distributed, 16000 J would heat 40 kg of water by a bit less than 1 degree C). So ... hmmm... if Light is not made of atoms this could actually work.