What do anvils do in Minecraft?

Answer 1

You can use them to repair weapons and tools by combining two of the same item in them, doing this also enables you to carry over or combine enchantments of the items. For example, if you combine a diamond sword of Smite I and a diamond sword of Fire Aspect II you will receive a single diamond sword of both Smite I and Fire Aspect II (if both swords have a damage value the damage value of the resulting sword will be increased). You can also change the name of weapons and tools from their original name. However all of these services cost you enchantment levels, so make sure you have enough levels to carry out the tasks.

Since Anvils are affected by gravity and will fall if no block is beneath them - much like sand and gravel - you can use them as a weapon by wiring up a simple piston trap, for example, and dropping them on the heads of unsuspecting mobs or players, if on a PvP server. However, dropping an anvil will cause them damage (which is shown by cracks on the anvil, the larger the cracks the more damage has been dealt to it) and will be destroyed completely if the damage becomes too much, it will not drop as an item you can pick up.