Oh my God, you're right! I was asked about this word by a friend who said that he had received it in an e-mail from a client in Italy with the explanation : the person that works the iron. In Italian, the equivalent for "smith" is "fabbro", no similarity to "dubalcain" whatsoever. But then when you opened my eyes, I searched on the internet and found that it was in fact Tubal Cain of the Bible, " the forger of every cutting instrument of brass and iron". It makes perfect sense now. Thanks for the suggestion!
Alitza