Alistar, Sergius is very much correct. Stone hammers, axes, and even plows (well, more like hoe and adz type tools) dominated the ancient world. Egypt and Babylon had massive stoneage civilizations. so did the Pueblo and lots of other American Indian tribes. Cambodia... China... basically every "cradle of civilization" type region on the globe. (edit: also, rare metal instruments were used in stone-age cultures for surgery, especially for things like trepaning which the north american indians had some success at. so Sergius is correct there too. Obsidian can be sharper, and is used for fancy scalpels even today. But I dont think it got much use outside central america.)
also, bronze edgemaking was never "lost". the bronze age didnt end because iron was better. Bronze is an alloy, and its components we're relatively rare. it was harder to make than Iron, was HARDER when made, and kept a better edge. it was pretty much superior in all ways, and weapon tests in DF bear that out. The Iron Age in the medeteranian region came about because of resource shortages, bronze could not continue to be produced in the quantaties needed. There was a piracy boom as people raided bronze artifacts to smelt down to make weapons out of. Iron was plentiful, so it was used as an alternative.
Steel was developed to counter the numerous shortcomings of Iron, and it took quite a while to figure out. doubtless, this was one of the reasons alchemy was such a big deal.
There are detailed armor vs weapon testing threads elsewhere on these boards, if you give them a quick search. the new model of things makes density very important for blunt weapons. platinum group elements are the highest density things on the periodic chart, and the metalurgy numbers are pretty spot-on. Bronze should be better than Iron. Steel should still probably be a trump card, but if we're going into this much detail then maybe there should be different grades of steel. hard to say what plays better as a game mechanic.
edit: one of the things that DF fails to account for is velocity. the length of your lever when swinging a hammer is important. many of the best medevial maces were HOLLOW so they could be swung faster. in reality, mass isnt everything. in the game, it is the end-all-be-all of blunt weapons.