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You will meet the Blacksmith right after you entered the portal that Kaslo opened(the monk who helped you escape). He will open the portal once you defeated the Worshiper in the graveyard. In order to unlock the achievement, it is not enough to talk with him. You will have to get to a dialog (it will come up once you used all other dialog, 3 to be exact) where you can ask him about his profession. It is something like: "what are you, a blacksmith or somekind?"
Once you asked him the achievement will pop.