Miss A scratches me. She does it in a kneading fashion, like a cat, while nursing. It is a comfort thing. It does not feel good though (yes, I keep her nails trimmed). At some point early on in our move I realized that I had tiny little scabs all over that one place (she only does this on one of my arms). About when we arrived in Colorado (likely the highest stress part for her) she started drawing blood. I can tell she is doing a bit better now. My arm is healing nicely.
She also bites. Mostly just me. Mostly just my arm/shoulder. She has a big brother that used to make a habit of this same behavior. She leaves marks and bruises. It also seems to be comfort related, but also teething. Sometimes she thinks about biting a certain big brother. He must stink, because she only gets within a few inches before backing off.