Percive Weakness

By taking this feat you may use your action to find faults in the fighting style of a single creature of your choice. To do so you must see the target.
You may either percive weakness in your foes:

Offense - 
If your target choses to attack another creature before your next turn your AC is increased by 1d4-2 for attacks from the target.

Defense -
If your target gets attacked by another creature before your next turn you may add 1d4+1 to attack rolls made against the target.