I've modified risers that have grips I didn't like. With a good grip, you should be able to draw the bow with the pressure of the grip against the V between your thumb and forefinger, and be able to hold your fingers and thumb open at full draw. Not that you should draw with your fingers open as a regular thing, but you should be able to draw and hold it that way if you want to. You shouldn't need any extra help holding onto it, wet or dry, just the light pressure of your finger(s) against the back of the bow to keep it from jumping out of your hand when you shoot it. If you want something that adds extra friction to the handle, fine, but don't let it be an excuse for holding the bow incorrectly.