A 25% absorb shield will not bring the warrior anywhere near the PLD when comparing their CD suites. What has made the PLD so strong is the fact it's mitigation scales off of INCOMING damage, until WARs have their healing bonus decoupled from wrath and are given some form of mitigation that scales based off enemy damage they will always fall behind PLDs in everything but farm content.

Iron Skin would have to be 50-100% of your HP to make it worth while @ 25% and 7000 HP a PLD with Rampart up only has to take 2-3 hits from a Dreadnought w/ 4 stacks and it's already beating it in terms of mitigated damage.

Maybe instead of the shield being based on your HP make it take a % of the damage you've recieved over the past X seconds, this goes better with the theme that a WAR is a reactive, not proactive, tank. We have high HP pools so we can take hits and then 'undo' the damage.