In many of the videos and tutorials I see people holding a hammer as if it were a knife, i.e. pointing the index finger over the hammer handle.

Before thinking this is fine, consider what happens to the hammer when you strike it on the bench block. There is some "push back" to your hands and especially to an extended finger. Do you really want that index finger to be continually pushed upward as you hammer? This becomes more and more dangerous over time; even the small jewelry hammer will eventually take its toll.

I hope, if needed, you will begin thinking more about your grasp and simply shake hands with the end of your hammer. Your hand will thank you!