Spoolofwhool

I believe Emperor's Soul comes between Elantris and The Final Empire since the first few Cosmere books were written in chronological order.

In Alloy of Law, the butler poisoned Wayne and he tapped gold to get over the effects. So it does appear that it can purge foreign objects from the body. Probably. How the gold heals you depends on how you view yourself cognitively. If you know about realmatic theory and how it applies to gold feruchemy, you could use gold to modify how you look or are physically.

I did state that you would need to somehow hack forgery to make it viable off-Sel. I have no doubt it's possible, it would just be tricky to figure out how and would probably be more inefficient. Something I can think of on the spot is taking a breath-infused object to Sel and using forgery on it. You would then somehow hack it so the forgery uses the breath instead. Question then would be whether the breath could indefinitely sustain the forgery as breath seems to never run out when used in awakening. (Exception: Nightblood, but it doesn't really use it for awakening) Moving on, you seem to have missed the definition of a shardblade which Brandon provided, which was stated earlier: "a heavily invested magical weapon" It doesn't necessarily have to be related to a splinter. We know this because the Honorblades are shardblades and they aren't splinters or containing splinters. (So far seems to be implied as such. I did find a WoB which was vague on the matter.) In any case, while you could possibly change a seon or a skaze into a physical object to act as a shardblade, it isn't the only method, just as using spren isn't the only method either. You could probably create a fabrial-based shardblade as well, something stronger than half-shards. Though, fabrials do use spren so maybe you do need something approximative of a splinter to create of shardblade... interesting thoughts about honorblades then. In any case, I do agree that Roshar, so far, is the most suitable for creating shardblades. This is mainly because they have spren everywhere which can be used as bases for them. There is, of course, also the extremely significant fact that Roshar had help devising the first shardblades. Honor gave them the honorblades which every known shardblade is based off of. Without a shard to show them what is possible and let them have an example to copy, it's probably a lot harder for someone to devise a method of creating a shardblade on their own. Not to mention that Roshar is probably the most invested world we've seen. Sel is heavily invested but a mess, Scadrial is low invested, and Nalthis is probably in-between.

Midnight Essence are probably related to the Unmade, so they might've been in the first few Desolations before the Listeners joined Odium.

In the annotations of Warbreaker it does say that you are changed by Nightblood to become immune to its nausea-inducing effects, not that you are ignored by it. This implies in turn that there is some connection to Nightblood. Also, there is some evidence that Nightblood does provide enhanced physical abilities to the wielders, as we see the thieves easily murdering others with by crushing them. While this could attributed to natural strength and the weight of Nightblood, the fact that it has occurred extremely rapidly and in close quarters lends more credence to magical enhancement. It isn't naturally easy to ram a sheathed sword through your chest. Anyone would have practically zero leverage. There is a WoB that a bonded Seon would lend similar powers if it and the person it was bonded to went to Roshar. This lends credence to the idea that Roshar gives some sort of abilities to people who are in some way bonded to splinter. Probably similar to what happens to the birds and the worms in Sixth of the Dusk. As you say, Nightblood is in essence a sword containing a splinter. Therefore, as an extension to above, there is a reasonable possibility that Nightblood would give its wielder certain abilities when on Roshar.

Change what order they could potentially belong to. You could use a soul essence to modify their values and everything so that they would be a match for another spren. Unless of course you're suggesting that you use the essence mark to change the spren by extension through the Nahel Bond as well. Problem with that that I can see is that you would somehow have to determine the qualities of the current spren and the spren you want it to change into. I suppose if you quizzed radiants enough it would be possible. An extension of that idea would be to use forgery to change normal people to fit the requirements for a spren to form a nahel bond so they'll have a higher chance of becoming a radiant. You would need to figure out a way to fuel forgeries on Roshar though.

She didn't need to change anything. It's just that his spiritual had become blank and the essence mark was to rewrite it to his original spiritual, more or less. Nonetheless, she did change it a bit, give him a bit more of a push towards revolution and improvement, but as I said, that wasn't necessary.

Forgery probably wouldn't work well since it doesn't add much investiture to an object. The inefficiency is probably due to the amount of forgery you would have to apply to the sword to make it gain enough investiture to be treated as a shardblade.

Gold burns off disease as well. I believe it was stated that Miles never got sick.

It was stated in Era 2 newsheet that you could use connection on individuals instead to get them to be more friendly with you.

Forgery overwrites an object's spiritual component, and by extension its cognitive and physical components. The emperor's spiritual had been lost, so the point of the essence mark was to give him a new one which matched the original as much as possible. During the book it is mentioned fairly extensively that Shai needed to know an object's origin in order to create a soulstamp for it. She did have to write about the history of the wall from its construction, or a fairly accurate guess of its construction. All soulstamps needs to enumerate a close enough history of the object being stamped if the stamp is to hold. So yes, they would've needed all that research into making the essence mark regardless. And at that point, it would've probably been easier to just replicate what had been done instead of changing something significant like a wound.

First point, we don't actually have anything which indicates either way. The WoB in question was just in response to whether a fully charged metalmind could resist a shardblade. It said nothing about the size of the metalmind or the total sum of investiture in it. In addition, that lends more credence to the fact that it has to do more with the investiture/volume ratio than the total investiture. Second point, you're wrong on that count unfortunately. The Bands, along with the medallions of the Southern Scandrians are not normal metalminds, at least the nicrosil portions are not. They have been altered so that non-soulbearer ferrings can tap them and gain the abilities stored within. WoB

Either way, there would still be the need use an Essence Mark on the Emperor, because your suggestion still requires forgery of him. As such, there would still be the need to do all the research about him. Main reason I can think of is that people know that he was hit in the head, at least his rivals were. If he were to appear with no wound to the head and a wound to the shoulder instead, then they would know he was using an Essence Mark and it would probably be bad. This way, they don't know about the Essence Mark altogether. Need to give it a bit more thought. Good point though.

Nor does he appear on Threnody.

I addressed this. I'm talking about the investiture of each infinitesimally small component. I think how an object is considered invested is by the amount of investiture in it compared to its maximum limit. Also, you forget the fact that the object also has to be magical. I do not think that "invested = magical". Magic implies that there has to be some shape to the investiture, so it performs some effect. The magical effect of the bands is that they could be used by anyone, not just a soulbearer ferring. Possibly. You can invest into a hemalurgic spike, as the hemalurgic charge is just a bit of investiture. Invested objects can be invested with different forms of investiture as long as you don't hit the limit for the object. There could probably be a way to manipulate stored identity, connection and memories to actually render a metalmind, or intertwined set of metalminds, sentient. Would be interesting.

It's been theorized that Nightblood will grant surges because it essentially contains a splinter as well, since the breath inside it is sentient. As such, bonding to Nightblood will possibly create something similar to a Nahel Bond, granting some equivalent of surgebinding capabilities. However, you are correct that it may be more akin to to Honorblades in how it grants surgebinding and other abilities as it will probably only grant the abilities to the current holder, instead of having one dedicated person it is bonded to. Regarding the evidence of smoke, I thought you were referring to that as evidence for something other than the obvious fact that Nightblood is indirectly modeled after Honorblades and has similar effects. My apologies. Although, the reason for the smoke is fairly different I think. The burning eyes might be akin to the saying "eyes are the mirror of the soul", so when a sprenblade or honorblade kills someone by cutting their soul, the "mirrors" (eyes) shatter (burn). tl;dr Nightblood is somewhere between a sprenblade and honorblade. It seems like it contains a splinter, so could form a Nahel Bond, but may just give abilities to the holder like an honorblade since the bond it forms is more versatile. Whether it is more towards one or the other, I don't think can be said because it was directly modeled after the former and indirectly modeled after the latter.

A fair example is when Wax fell through the floor while they were inside the bubble. I believe it was stated that doing so burst the bubble.

I know about that, but it's inherent to sprenblades as well. The OP seems to be suggesting that there is a dark smoke effect in addition to the burning eyes effect, which is what I was asking about. Unless of course the OP is just referring to the smoke from the burning eyes, in which case it's not worth mentioning as a supporting evidence as its clearly more an effect related to cutting the soul than something specific to Nightblood and Honorblades.

Yes.Usually bursts it though.

You could, but it would completely ruin the point of the fever. When you're sick, your body starts a fever to raise the body temperature in order to kill the virus/bacteria causing it. The fever breaks when the body deems that the virus/bacteria is gone and returns to normal. If you store warmth while you have a fever, you would stop the fever, but would still stay sick. I imagine in might actually be better to tap warmth when your sick in order to kill the sickness more quickly, though you would have to make sure you don't start doing extra damage to your body from the heat.

I imagine they were easier because the Listeners weren't on Odium's side until after spren started bonding with humans. So yeah, more of a balance, because the formation of the Knight Radiants indirectly caused a race to turn to Odium and gain powers to counteract them.

I don't recall Honorblades doing anything of the like. Can you quote a passage?

The thing is, I don't think the size of a metalmind impacts the investiture density, which is probably what determines how it can resist other invested objects like shardblades. You could take a 1 mL metalmind and a 1 L metalmind and fill them with the same amount of investiture, and I imagine the smaller metalmind would resist a shardblade more easily. This is because the investiture would be equally distributed and each piece of the metalmind would have more investiture. As such, the Bands can probably be considered one of the most invested metalminds we've seen, and would be just as invested as a fully charged sword. Your point about simply being able to fight a shardbearer isn't the point. We're talking about making a shardblade, not defending against one. Yeah, defending against them isn't hard. As we've seen, people have made half-shards on Roshar which defends against a shardblade. However, this does not make them shardblades. As such, I think my point that shardblades need to be heavily invested with a magical effect still stands. Nightblood, spren blades and honorblades all have effects. They can cut through realms past the physical and honorblades give surgebinding capabilities, among other things. I don't think these are effects which are inherent to shardblades. They're just based off the original Honorblades which could do that. As you say. the difference is just the thing it cuts, but a fairly significant difference in my opinion. Effects don't have to be flashy or obvious, but they still need to be a step up than just a sword with raw kinetic investiture in it.

Exactly. It's probably possible to do with many, if not all, systems, so more than likely it has nothing to do with feruchemy for most worldhoppers.

Probably this honestly. It has been said that different systems can achieve similar effects so I imagine that another system could achieve a translation effect.