Is it possible that the Death Rattles are the words (or maybe thoughts) of the Herald Talenel as he is being tortured by the Voidbringers?
They often talk of the Unmade as if they are there.
The Death Rattles themselves come from one of the Unmade, which it makes it interesting that they are helping Taravangian accomplish his goals by revamping the Diagram, but the Thrill affects both humans and listeners so...
Anyway some Death Rattles that were especially interesting:
WoK Ch. 58 "Re-Shepir, the Midnight Mother, giving birth to with her essence so dark, so terrible, so consuming. She is here! She watches me die!"
WoK Ch. 54 "The burdens of nine become mine. Why must I carry the madness of them all? Oh, Almighty, release me."
WoK Ch. 2 "Ten orders. We were loved, once. Why have you forsaken us, Almighty! Shard of my soul, where have you gone?"
WoK Ch. 59 "Above the final void I hang, friends behind, friends before. The feast I must drink clings to their faces, and the words I must speak spark in my mind. The old oaths will be spoken anew."
I suppose these could come from many sources, but they clearly come from people who are very well informed. They probably aren't leftover from Honor, as they Death Rattles come from one of the Unmade. Maybe they come from all the Heralds, or from the other Shards on Roshar, or from others like Hoid.
One of the more interesting Rattles: "Three of sixteen ruled, but now the Broken One reigns." WoK Ch. 11 The Broken One sounds like Odium, which would mean the three of sixteen would be other Shards, but I thought that only Honor and Preservation were on Roshar, and at some point Odium, but if the Broken One is actually Odium then who would the third Shard be?
