The soul thing i mentioned is available only for Morphidae, since they are technically souls with magic (these guys are the angels of my world in a way, so there had to be smth that made them special and unique). The rest of the creatures in my world are the typical whisp like soul + body thing, nothing special.
As for the separation thingy, thats a physical process; you would even be able to touch a Core if a Morphidae allowed it (the core looks like a shiny marble thats very hot to the touch - its usually located in the chest, reason why a Morphidae's chest is incredibly warm)
Aside from creating daemons like Rin, there isnt much else that involves a Morphidae's soul (the separation thing was invented by an enemy of these creatures and is considered an atrocity by Morphidae, since it kinda means a fate worse than death, and its highly offensive).
The only thing that does involve the soul and is perfectly normal would be reproduction. Yea, these guys use their souls to do that, since they lack the uuhh.. reproductive organs. What they do is, they heat up their soul until its liquid and then mix about 35% of it with their soulmate's other 35%. That soul mass gradually solifies into a new core, which in turn starts producing the magic layer to coat it (thats when the new morphidae develops a physical body - the core is the most important part of all, so it takes the longest time to be fully formed)
One Morphidae character can create a sword from his Core materia, but hes the only one that can do it, since he was originally born from a stone (long story here) and he's also evolved into an angel already - the guy was an anomaly so he could do a lot of stuff, there he is in case u wanna take a look :0 —> Kiah