Hmm

I suppose that really would depend on how possession works in this setting. Typically speaking, being possessed by something gives the person possessed a few...unique attribute in most settings so I was going with the norm there. Sometimes its strength, other times its just being really durable. At least, that's my thoughts on it. It wouldn't be anything too amazing to start with, just something like maybe being able to levitate a few feet awkwardly off the ground.

If you're not comfortable with it though, I could easily come up with something else to be her main trump card, so to speak.