The shield is PLD's mitigation gimmick, all the tanks already have one (WAR has self heals, DRK has the parry-Reprisal fusion that basically functions like a built-in Eye for an Eye). So I wouldn't want to see that kind of free passive mitigation just handed out on a platter to DRK and WAR. They don't really need it.

The only way to make Parry meaningful in my opinion is to follow the Wrath - Abandon model where Parry is converted to Crit between MTing and OTing based on stance. I.E eliminate the stat and just convert Crit into Parry when you go into tank stance, or the other way around and elminate Crit from tank gear and just convert Parry into Crit when turning off tank stance/turning on DPS stance.

Its the only way to not make Parry conflict with DPS stats. And I hate the ideal of just putting it on a Weapon a la rate/strength stats on PLD's shield, or just slapping it by default on all of our gear as a 3rd secondary, as it eliminates the need for the stat period if its just a thing that goes up whether we choose to or not why not just code it into the job itself? It would also have to scale insanely slowly so as to not reach a point where we're parrying everything.