[quote=@Weed]
Sorry for the double post but I wanted to make sure this wasn't missed. I'm curious about death in this game. More accurately about the soul. What happens to the soul if a demon kills a human or angel. What happens when a demon dies? Since there is necromancer I'm curious because I intended on strengthening my summons by taking the souls of the fallen. But maybe that would only work for demons.
[/quote]

The souls of demons and angels are indistinguishable from their body. Their bodies are only manifestations, hence eternal life. In-betweeners on the other hand have their soul within their body and that is released once they are killed. 

If and Angel is slain, they will return to heaven. If a Demon is slain, they return to hell. At this point, the process of returning to the earth realm, even with the dimensional breaks, takes about a decade (unless summoned via contract).

When an in-betweener dies, their soul is trapped on another plane of existence here on Earth. Before the dimensional break down, souls would naturally gravitate towards Heaven or Hell, depending on how they lived their lives. With everything out of wack now, souls will stay stuck in limbo here on Earth until a demon or angel forcefully takes the soul back to their domain. 

Does this answer your question?