It looks like a struck tool not a hammer but that's what the fellow has it listed as on eBay.
http://cgi.ebay.com/Old-Mueller-Hammer-Blacksmith-Cooper-Farrier-Tool-or-/190412533698?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2c5578afc2
Has a bent wood handle, brobably steam bent I'm guessing while green. Maybe offset to make a hole for wedge?

rectangular punch, like for the thumb latch on a Norfolk style door latch?

My guess would be a creasing tool for horseshoes... just a guess though.

I think the bend is for convenience like a power hammer tool.

brad

cooper tool, for setting the rings?

Hey Sam, That is what I offered coopers band setter.

I'd go with slot punch myself; a band setter should be offset to one side so you can get close up. (just made a couple dozen band nails last week for a cooper)

I'd go with slot punch myself; a band setter should be offset to one side so you can get close up. (just made a couple dozen band nails last week for a cooper)

It IS offset though, plus has a little curve to match the barrel... must be a band setter. That seems obvious now.

I should have looked at the other pics; you're right!

It's for hammering round corners, you can hide behind a wall and no-one will know you're there.

it may be what the British term a siding-down tool for setting or finishing shoulders as with a set hammer. The curve may have been for specialized, repeated work. We don't know what the final product was. The curved haft got your hand away from the heat.

preserving the image for the discussion's sake