clemency serves as the way to reference how Paladins/knights are able to cast healing magic to heal itself and others from the classic FF along with how Cover is the core mechanic for PLD in series past.

generally in practice, Clemency is a strong on demand GCD healing magic as it is the only tank healing tool not on a cooldown, but bc it is a GCD. using it will drift its GCD from its main rotation, but it is still quite a good heal self/frail party member button, the MP requirement isn't much of an issue current expac since PLD only needs about 5000 MP for its total burst.