Given the style of handle, it looks like maybe a pry tool (for something like hubcaps for example, or to part the two halves of a mold) or for something with a big slotted quarter-turn latch like an electrical panel. The way the handle would be grabbed, it's going to be something for twisting or prying with a relatively small range of wrist rotation (not multi-turn like a screwdriver). Looks like a T-handle with a curve to put your thumb on.
