Re: What in the world is this bayonet for?
I don't think any soldier was making bullets in the 1880's; I had in mind something like heating food or rearranging wood in a fire. It may well be a one-off, showing someone's bright idea to solve a problem that might or might not exist.
It wouldn't even have to be connected in any way with the military; an old bayonet could just have been a "platform" to use in making a device having no connection with its original purpose. I recently saw something like that used on a TV "How It's Made" (or one of the similar shows) to flip over pieces of plastic coming off a stamping line. (I forget what they were making.)