Nitpicking

You could argue that with the importance of the Cognitive Realm, if you convinced enough thinking beings that it's possible to steal basic biology, it would be, but at "the moment" (the time of Wind and Truth) that is not the case that we can tell in the Cosmere. I suspect Ruin (now Harmony) would have to intervene to change hemalurgy in order for it to happen. I think if Brandon wanted more horror elements, he might introduce an atium alloy that permits stealing biological form and physiology. You could spike out, say, a a beautiful woman's form (leaving behind a dead mistwraith-like blob) and the person who received the spike would become her physical duplicate (except for the spike itself). It would be a horrible, evil way for short-lived people like humans to obtain physical immortality. If a spike had time to degenerate outside of a living person, it would produce a horrid mangled creature of mismatched parts from the original form and the stolen one. The evil immortal would try to find more people of similar appearance to the first victim to spike, to "perfect" their new body, leaving a trail of blob-corpses, and Brandon's old idea of a bunch of Misting-cops would have to track the person down ... did I just write the elevator pitch for a Mistborn side-story?

Wasn't she named that before Vorinism (where that symmetry custom comes from) came into existence? Afterthought: I wonder if Rayse learned to Splinter and Unmake from the experience of killing God and stealing his power.

The Sibling doesn't say "left Roshar," just "left". (Chapter 21) Brandon will sometimes remind his fans that the characters, even really old and knowledgeable ones, don't know everything and can be wrong.

Proposition: Ba-Ado-Mishram is The Night, Unmade by Rayse. Support: The Night was an Adonalsium spren. Mishram's name includes "Ado", one of Adonalsium's nicknames. She Connects to all of Roshar on a deep level. The Nightwatcher was made partly from The Night's Investiture. BAM's form seen in W&T Chapter 13 looks like the Nightwatcher to me. Who else would have power seemingly just barely short of a Shard's?

FTL means time travel to the past, full stop. Relativity allows FTL via wormhole, and that does result in time travel and acausality. Brandon will ignore this under Rule of Cool.

And some are rare and thus expensive, like gold .

A metalmind can be given enough Investiture and the right Command, which causes it to become aware and able to act without another sapient being giving specific instructions. For instance SPOILER FOR ISLES OF THE EMBERDARK More generally, it's possible to Awaken things with methods other than Breath, but the underlying Cosmere mechanism is the same: gather enough Investiture that isn't already associated with a sapient being in one place and it tends to become sapient. IMMEDIATE EDIT: I don't believe we have seen an Awakened metalmind in Mistborn itself to date, a lot of this is from Words of Brandon and stories that take place in the future of The Lost Metal. TLM does have an "Identity Lock" that could be a primitive Awakened metalmind, I guess.

Have you thought about the timing? The Coinshot would have to wait until the aluminum bullet was fired and passed through the cloud of dust, and only then start Pushing (or she'd just push the dust away before the gunshot). That's some mighty fine reaction time you're giving the hypothetical allomancer, to start pushing in mid-bullet-trajectory. It's probably easier to do what Wax did and dodge like crazy.

We're all just speculating. I think the Exist dawnshard modified Hoid's soul, and also gave him so much Investiture that even his "Spiritual Shadow" in the Spiritual Realm has enough Investiture to become sapient the way Honor almost(?) has. It's not different (in my opinion) from the way the Blackthorn spren is now a sapient being, and it's like (but not the same) as the way the Stormfather created Sylphrena. Once the Hoidspren was there and sapient, like GG0z said, it would have Hoid's knowledge of the Cosmere and realize what had happened. As Brandon wrote about in Snapshot, it isn't fun to suddenly realize you are only a simulation of a real being, and you'll shortly poof into nothingness.

What about what? That avatars might not know they're avatars? https://wob.coppermind.net/events/467/#e14744 Note the thread title. Jasnah as Autonomy's avatar is a crackpot theory. (Doesn't make it false.)

I said in another topic that Taravangian was expressing the bad side of Preservation. All the Shards are expressed everywhere in the Cosmere, after all, even if the Vessel's awareness can't comprehend everything. Endowment's Investiture Preserves the Returned, after all. Preservation's gift of bits of Itself to all Scadrians (making Allomancy possible) is clearly Endowment (which just means gifting). Kelsier is very, very devoted to keeping Scadrial Autonomous, for that matter. Shallan clearly shows Virtuosity in her art. Nobody would argue that Kaladin isn't Valorous. Jasnah is Devoted to her scholarship. Etc. Taravangian is putting himself in opposition to Endowment, maybe. Stormlight used to be a free gift to anyone on Roshar, after all. Now Warlight is something you have to pay for, with prayer to Retribution.

It doesn't, that I know of. Heralds have unlimited access to Stormlight. They don't seem to be able to fill gemstones like a Bondsmith, but they never run out of Investiture (just as the Fused don't, or Elantrians).

I question whether a Radiant could use Lerasium, though. It's the God Metal of the wrong Shard. It might be hard to be Connected strongly to both Honor/Odium and Preservation/Harmony). I'd bet money Brandon would say that it's possible to do this, but difficult because different Investitures oppose each other.

According to one canon book, Chaos lives in Silverlight already, of course.

Little known fact (outside this fandom): Warbreaker was written as a prequel to the Stormlight Archive. Also something @Deception might want to know: you can read it free. Check out Brandon's web site.

I am of the opinion that if Dalinar had taken up the two Shards (which he could have, he had Connections to both), they would have become Justice.

Depends on when. Before Vin takes up Preservation, I presume, but is it before Kaladin becomes a Herald and almost simultaneously a Fifth Ideal Radiant? Herald Kaladin is nearly unbeatable. (Nearly.) Note that he has advantages over even most of the Heralds, because a Radiant uses Stormlight more efficiently than a Herald. He can tap huge amounts of Investiture then use them really well.

I can argue that someone like Treamayne or Chaos would be the most powerful of all. They've read the books. Chaos has actually advised Brandon on creating the Cosmere. (I don't know if Treamayne is also a beta reader.) I mean, unless you let Brandon be the normal person ....

Except the Nightwatcher, Cultivation's "daughter". I would be amazed if the Nightwatcher can't give Lifelight to Radiants, should she decide to. The re-creation of the Heralds protected the spren, including the Nightwatcher. And except for Ba-Ado-Mishram, but she's currently in the Cognitive Realm (as far as we know). Technicality, but at least two Heralds are Fifth Ideal Radiants, who have access to unlimited Stormlight even though Stormlight doesn't exist. We know that Towerlight still works, and that's half Stormlight.

There's also a scene that used to be on Brandon's web site where Hoid and Frost have a conversation in person.

The Singers, to draw another comparison, change forms the same way that Reshi king sex-changed. The spren in their gemhearts changes their self-image, and the power of the Highstorm lets them "heal" to their correct shape, as they now see it. Note that the enormously more powerful Fused spirits (Cognitive Shadows of dead Singers with additional power granted by Odium) can continue to change the forms of the bodies they wear over time, gradually becoming more like the Shadow's original body. Kaladin comments on noticing this in Leshwi. Fused can continuously draw Voidlight directly from the Spiritual Realm without needing a Perpendicularity, exactly the way the Heralds can draw Stormlight (but apparently more slowly). One wonders if the Heralds also shift, if maybe Kelek looks wimpier than he did 5,000 years ago because of his mental issues. One also wonders (or I do) if the Singers could literally heal in a Highstorm, if a gravely wounded Singer should be left out in the storm in the hope of "changing form" to a healthy Singer. And it's clear in retrospect, that's what pre-Oath Kaladin did to survive his punishment waaay back in Way of Kings.

There's also dragonsteel, which acts more than slightly like a god metal. One wonders if it's Adonalsiumium (Adonalsium's god metal).

Hmm ... From Rhythm of War, Chapter 102, referring to Jasnah. Jasnah is an avatar of Autonomy! We know from Words of Brandon that avatars don't always know what they are.

I don't think it's unique. Animals (e. g. rhyshadium, chasmfiends, Ancient Guardians) can attract spren. I think it's living animals that attract them, especially smart ones. The Singers are uniquely less attractive to spren, it is implied, precisely because they are more Cognitive than humans or horses, the same reason they can take Forms and naturally hum the Songs and Pure Tones and such. It's a difference of degree, not of kind, but it seems to be real. So, Cognitive entities seem to attract other Cognitive entities less.

I wrote that Retribution was "trying" to kill him. Remember, Taravangian's plan was to Unmake the Sibling. Warlight is restricted to those who pray to Odium, and I can't see Vasher doing that. Lifelight is probably thin on the ground with Cultivation not on Roshar. Lift can presumably still create it by eating, but we haven't seen her share it. I suspect the Nightwatcher is also capable of supplying it, but she's both unwilling to help foreigners (worldhoppers) and hard to find. Note: I don't think Odium was deliberately striking against Vasher at all, I was just being witty. I suspect Vasher would hold it against him, though. (As Rayse said, being hated is Odium's job.)