Just a comment about your example of Smith as a surname, there were other smiths besides blacksmiths, any metal worker was a smith, coppersmith, tinsmith, silversmith, goldsmith, etc. By the way, contrary to popular opinion, a blacksmith did not just shoe horses, he was the source for all metal products; hinges, hooks, pots, pans, gates, locks, a smith made just about any of the things made of metal that today we would buy in a hardware store.