I agree with it being a blacksmith's cutting tool, but whether for "hot work" or "cold," I don't recall the give-away distinctions between the two versions. The one "hammer" — inexact because it was struck by one, not used as one — I used to own was for cold cutting. Maybe the hole was provided to temporarily hold a "pin" to keep it from being driven inside, say, a barrel when one is removing one end of one? Okay, go ahead and sneer or snort — I say that at times there's nothing wrong with blue-sky speculation. *he quick carpes the diem and snorts @&w/ himself*