I did one real similar to that about 10 years ago, swinging a large hammer with all my might and holding a punch with the other hand up side down, something slipped, got out of calibration, and dead on the thumb.
Then comes the vagal response. The sight of blood and injuries don't bother me, but after an injury my scalp and tongue go numb, blood pressure drops, begin to sweat, and get nauseated. So I have to prop my feet up to prevent passing out. That is worse than the injury itself.
Been real fortunate over the years, as much as I've been involved in. Don't take safety for granted. And chainsaw injuries I hear about, ikes, wear chaps guys. I'd rather get shot than get a chainsaw in the leg.