My first post vise has a gentle double curve in the handle and lots of small nicks. Both appear to be intentional modifications. The handle tends to stay where it is put, and doesn’t drop like a rock when stopped in a vertical position. When it does drop is sort of works it way down slowed by the curve and nicks. Also the curve seems to give it a self adjusting ergonomic feel.
I have wondered how far this idea could be extended practically. I’ll probably never get around to try out variations. I did make a sketch of a handle with a bit more radical curve but didn’t add the transverse nicks to the illustration.
I usual add additional safety feature to my post vises to help prevent getting pinched between the handle ball and the screw shaft hole. I run a bead of silicone caulk around the shaft where it joins the ball then I wrap a 3/16” diameter leather strip around two or three times and tie it. When dry this band acts as a soft bumper which prevents pinching. The leather is quite tough and the silicone has enough adhesive power to keep it in place.
Other references to vise handle safety.