Weapon carrying mobs change weapon if the current one is ineffective.

Say you are battling a skeleton, you keep deflecting all its arrows with a shield. To make the challenge a bit harder (maybe if you are on a harder difficulty) the skeleton could have the ability to recognise this and would change weapon to for example a sword to see if it is more effective against you. If you don’t think all skeletons, pigmen, etc should do this then perhaps these mobs could only do this after watching and learning from the mistakes of another mob of their species? Either way I’d think it would spice up the fight a bit more, what do you think?