Many players do not understand how to use the new enchanted books as a book could have protection 3, fire aspect 1, and luring 3. That happens is that you use a piece of armor in the anvil and the book, and whatever on the book that can go on armor will go on the armor piece. Put in a sword and whatever can go on the sword will go on the sword. Put in a fishing rod and whatever can go on the fishing rod will go on the fishing rod. Depending on the item you enchant, all enchantments not used will be not used.
