Tekka originally meant the state of red hot iron as well as sparks generated by the forging process, and it came to refer particularly to teppo kaji (gun smithery) and also to katana kaji (sword smithery), latter of which has been closely related to Shinto rituals and samurai warriors.
鉄が赤く焼けている様や鍛冶仕事の火花でもあるが、そこから鍛冶の中でも神事や武士との繋がりが強い、刀鍛冶・鉄砲鍛冶を指すようになった。