I've never seen a cat do that to a human. She must have done this kind of thing before.
Cats are nasty little buggers. They are also alot stronger than people think. I had a friend who's cat went psycho on him and it required a hospital visit, stitches and a couple weeks off from work.
Still..he couldn't part with it.
I went to a friend's house once and he had a cat that was huge. I didn't even notice it but when I did, I was afraid of it. It's head was as big as a bowling ball, lol. He said it was harmless but it was really scary. I didn't want to upset it at all.