And, now the Bad News
1, it's not an antique, still produced & sold
2, It's not a blacksmithing tool
3, It will hurt if you hit your thumb with it.
That hammer is made to work with PunchLock hose clamps, and is soft faced so it doesn't damage the mating face of the punch it hits.
Auctioneer is only honest 90% of the time, possibly lower when he says antique.