you can do that
just put it on the anvil and hammer it
You should add upgrades to the shop like (these are just examples that i think would make the game cooler)
bigger furnaces, imps that give customers their weapons, local knight tournament(if the knight that bought your weapons or armor wins you get a 30% of the winnings, 2nd place 20% etc.., mines behind your shop to explore and get metals from, a blacksmith tournaments where you compete against others to become the ultimate blacksmith!
I think this game has a lot of potential and i cant wait to see the next big update.