"So you're saying that you want for me to run around and get stabbed so that I can use my ability?" Sam was looking at her as though she were the dumbest person in the entire world. "Newsflash! I don't have the ability to heal myself if I get STABBED TO DEATH."
This wasn't a freaking movie. Sam wasn't a ninja or some kung fu warrior who could take that sort of stuff. He was just a guy with...demonic powers.