Minecraft wiki entry for Before_1.8, associated text: The anvil can be used to combine two items of the same type, or an item with an enchanted book. This applies only to items with durability: swords, tools, and armor. The first/left item is the target item, the second/right item is the sacrifice item, which will be destroyed. Combining two similar items does either or both of two things. Each of these costs levels, but if they're both done at once, part of the cost will be shared: