I know a guy that went toe to toe with a knife wielding attacker. He's a black belt in tang-su-do. He also didn't know the guy had a knife. He's damn lucky he didn't bleed to death. He said he was hitting the guy with everything he had and the guy was "punching" back. He was actually stabbing back. The guy took off after my friend dropped to the ground. Cops showed up right after and called an ambulance. They eventually caught the other guy. He had a broken nose, jaw, and crushed eye socket. Broke three ribs and some wicked bruising all around his chest area. Unless you can drop one of those x-fighters with one or two hits, hands against weapons is a really bad idea.