The assumption is that the ball is hooked in. Something is then attached at the bottom. That would then fit all the keys that I found in the immediate vicinity
I think that the U-shaped metal sheet was riveted to the belt and then something was attached to the ball end of the pendant, such as a knife sheath. The strange knife sheath fittings such as VT-P49HR93Z have a metal spring on the back and were probably attached to the belt with some kind of mechanism.