I don't see how this squares with Silas' claim that a 15-lb dumbbell hurts your hand when you rest it on it.

OK, I just tested this by balancing the end of a ~21 pound dumbbell on my palm while my palm rested on a counter (surface area of dumbbell end looks to be about 0.60 square inches, making the pressure around 35 psi, or about 2.3 atmospheres?) It was a little painful, but I didn't cry out or feel the need to get the thing off immediately. So in conclusion, I think Silas might have been exaggerating.

Resting my palm on a pillow instead of a counter, I don't really experience pain anymore, just discomfort. Maybe that has something to do with the fact that deep diving doesn't cause pain?