Your axe says that it deals 10 damage, right? So it deals 10 damage, right? WRONG, Mobs in minecraft have armor, the most common one being 4 (2) In zombie type mobs. With this target dummy, you can check the real damage your weapon would do against zombie type mobs. You can also check your damage when you have strenght potions and use critical strikes, it will always tell you the real damage that you deal!