Where'd the spray of blood come from? The dude bit himself? What artery in the mouth did he bite? Why do you think cutting yourself anywhere in the head would be a good idea in a fight? Like, have you ever cut yourself in the face shaving? That shit doesn't stop bleeding. How much blood is he losing? IIRC, you can lose 30% of your blood before fainting. An adult male has like 3 liters and most of it is in the spleen.