if your character discerns by smell, touch, sight or sound (or for some reason taste) Grace is a perfectly normal human being, if a little heavy on the iron content. If your character can see auras, sense magic, or read minds Grace is only a facsimile of a human. her soul is only partially human, with the rest being the spiritual equivalent of "filler material", she constantly gives off a kind of magical static, making her a beacon for things that track by magic (like wraiths), and her mind is fragmented, split into two like a human's could never be.