I managed to dig out one to photograph. All three that I've seen appear to have once been candle stick holders, but were "salvaged", the thick brass arm sharpened and tapered, and the deal worn on the thumb. This is according to the elder Amishman I spoke to who said his grandfather had used one. As well, one is listed in the Norwich museum which is identical also (sharpened to a knife edge).
RPG, I'm, thinking now these gimmicks of mine and in Norwich probably don't mean much, except for the fact that some things could be easily substituted for others. I stick an old spud wrench in my tractor hitch because it fits, but it is no more a clevis pin than a ground down broken candle holder is a corn husker. When I dig out the other one I'll compare the stub that was ground down, and as well, I'll ask my friends to show me the ones they've found and see which are accidents and which are intentional. Meanwhile it's probably safer to call this one of mine a "re-used part".