I think Dragon's Dogma gave 2-handed warriors cleave on their attacks. I don't really see much of a problem with giving DRK and WAR cleaves on their auto attacks and letting PLD do a higher potency auto-reprisal cleave with the shield that activates upon a successful block but cannot proc more often than an auto attack. It'd be a nice way of boosting their AoE damage relative to the other tanks since Flash is underwhelming in dungeons compared to what DRK and WAR bring.