This happens when I use a hammer for extended periods of time. I never really worked in construction or carpentry due to a crippling fear of heights, which fucking sucks to say the least. My brain loses its ability to control my legs and arms, vertigo kicks in and I move at a snail’s pace. But oddly enough I am able to use climbing treestands for some reason. I do use a fall harness though, so maybe I’m just scared shitless of falling. I also have titanium rods holding my pelvis together from a workplace accident when I was 19, so any significant fall would probably leave me paralyzed. But anyways my hand cramps up after a while of swinging a hammer , that’s when Ive experienced the death grip, probably just poor form or lack of experience swinging a hammer.