It appears that the ax handle has been cut down to fit the eye of the weight. My guess is the ax handle isn't what originally was in the eye of the block of metal.
I was wondering about that myself... Granted, when I fit hammer heads onto handles they often look like that, so that's not a given... but it could very well be a piece of some large machine that happened to have an axe-handle-shaped hole in it that someone decided to handle for.... some reason...
But, I have no clue :P And knew that someone on here might be wizardly enough to recognize it.