Here's one. Good buddy of mine way back in high school. He was working on his 1970 Chevy truck front end. He had a 12" crescent wrench trying to remove a large nut on the front end of his truck. He was pulling the wrench towards himself. Wrench slipped off the nut and smashed himself in the mouth. Couple teeth fell out, blood everywhere and his lips were busted.
Think about that. A decades plus old truck. All the nuts are very large and rusted on. Kind of nuts an air impact will not get off. He was pushing with his leg on the frame when the wrench slipped.
slomo