There's a bug where you can create items with the wrong number of ingots by putting the correct number of ingots on the anvil and selecting the style of weapon you want and then adding or removing ingots before hitting them. For example you can craft a Greatsword with a single ingot by putting 3 ingots on the anvil, selecting the Greatsword style "0" and then removing 2 ingots. Interestingly this will often result in a different style of Greatsword than you first requested and you can choose to go the other way and craft a dagger with 3 ingots. This also works with Hammers, Shields and Axes so long as you leave the minimum number of ingots for that class (for example you need at least 2 ingots to make a Pickaxe).