Maybe it is an optical illusion, but I believe that I see a hole at the point in the frame between the grips that would likely contain a screw (lower arrow). and the upper arrow is pointing at the toggle knob, where a close examination shows that the toggle knobs are apparently held on with an allen head bolt/screw of some type...
We are no closer to identification than when we started folks... all we can say is that we know what it is not... the mystery continues... Most fun I have had on the forum lately... with over 3500 members world-wide, you would think that one of us had seen a specimen like this before!
My next guess? ...perhaps a converted blank or starter gun?