The hammer example made me remember something. I did some Aikido long ago, and the instructor spent quite a lot of time showing us how to grip things like sticks. As I remember it, instead of the instinctive way of just forming a fist around it, we should instead start from the little finger, wrapping the fingers one by one, but letting the index finger actually rest more along the handle than wrapping it. That way, supposedly, the grip is just as good, but more flexible and the index finger can help with control.
replies(3):