Mmmm Could make her a player controlled villain for now or something and give you all something to fight with the training missions that isn't just NPC after NPC. Makes her regen a good story device as to why she keeps coming back over and over. :P.

I just dunno about shimigami. Human characters are so... boring. I could make one based on portals, but then I dunno how you'd feel about the potential of telefragging.