Minecraft wiki entry for Combat, associated text: If you have a shield, try to use it at strategical moment to block 100% melee damage (only works in 1.11+). If the opponent has a shield too, it is better to fight with an axe, since they do more damage and can disable shields when hitting a blocking player. If the opponent rises their shields, try to sprint hit him with an axe, then continue with axe critical hits while his shield is disabled. The opponent is at his most vulnreable state when having a shield disabled.