I'm sure it is old and might be cast iron, the smooth finish reminds me of one I have that slid off the pile fell on the floor and I have not seen the broken of portion! 12oz weight, one end is an 1/8" radius end the 1/4" radius end no markings, 12" length on the handle. I can not seem to find one similar in the catalogs or new ones.
Going thru some of the hammers and tightening up handles, about 1/2 of them are down off the wall from when we removed 1/2 the windows out of the shop to use in other building with bad windows. Going need to finish off the insides and put up the hammer holders back up.