This is a little safety device I’ve used so long it is almost invisible to me. My big Trenton-Fisher is at my main work station. This large vise has a handle which is massive enough that if it falls in the vertical orientation a serious pinch can result if the thumb-index web skin is caught by the terminal ball.
After such a close call I decided to create a bumper by wrapping a leather strip around the handle just below the ball. Later I added some silicone adhesive and even later used duct type tape. I use the vise every day and from time to time the bumper must be refurbished to remain effective.
There are five other post vises around the shop and none of them have handles heavy enough to present enough threat to require bumpers. One has a sinuous “S” curve bent in the handle which seems to have been added by a previous owner and is somewhat effective in preventing the potential free fall.