When her injuries were evaluated, this is what they found. Index and middle finger had been bitten off. Ring finger had been degloved, and had to be amputated. Two metacarpals were fractured. Ulna was fractured. Teeth marks more than half way up her elbow.
The point of this thread is to reinforce the idea that horses are bigger and stronger than humans. Do not risk serious injury to yourself to stop two horses from fighting. They can handle it a lot better than you can.