Oddly enough, this thing has been one of the more useful tools I've ever gotten hold of. It's a 2oz. ball-peen hammer:
You can find them new, only places I know are Brownell's gunsmithing supply and some watchmakers supply houses. I found this one at a flea market.
No, it's no good for pounding things into shape. However... in knife work, I use it for setting pins into place, for tapping a guard into place, I've used the peen end for giving a guard and/or pommel a hammered finish. In gun work, tapping pins into place, tapping a sight to one side or the other for windage adjustment(usually with a brass punch). With a wood block for padding you can move a tight part into place, like the gas tube assembly on an M1. Small rivits can be set, and so on.
Nice thing is that with the size of this, you'd have to work at it to hit a piece too hard, and it's light enough that making a lot of small, controlled strokes is easy.
As I said, a most useful tool.