I believe the origin of such phrases comes from original Colt revolver, the first greatly succesful revolver model. ("God made men, Colt made them equal.") I'm not well-learned on early revolver models, so that's all I can say.
EDIT: Bronze weapons were superior to early iron weapons, and continued to be at least equal throughout middle ages. The reason bronze was abandoned was not inferiority, it was cost and availability - specific countries had monopoly on tin, and eventually they started to run out, making costs prohibitive and necessitating moving to iron, which corroded more easily and was harder to melt and work.