reanjr I agree that a feat tree would be the way to go, but I am not sure about the 'create an AoO' twist...
Of course, I don't have much to add in that regard either
One HR I banter about, and forgot to save the out of the shield improvement thread was a relatively simple change. It went something like:
You can spend an AoO or an Action point to block an attack with your shield *. The attack must first overcome the shields hardness and hit points before damaging you. The shield loses 1 point of AC protection and 2 points of hardness for each 10 points of damage done to it. If the shields hps are exceeded, it is completely destroyed.
Keep in mind that each plus of a magical shield adds +2 to the hardness and +10 hit points.
* You must annouce this after the attack succeeds but before damage is rolled
* this means an object striking and dealing damage, not area effect spells, rays, etc..
{added}
Feat: Shield Expert
You have learned to better utilized your shield to defend yourself. You gain a dodge bonus equal to the number of attacks you may take in a full attack action.
Feat: Improved Shield Block [General/Fighter]
Prereq: BAB +4, Shield Expert
You excell at protecting your weak spots. When blocking an attack with your shield, the attacks critical multiplier is reduced by 1 and the shield gains +5 hardness against the attack.
Feat: Greater Improved Shield Block [General/Fighter]
Prereq: BAB +8, Improved Shield Block
You have mastered the defensive art of the shield. When blocking an attack with your shield, the attacks critical multiplier is further reduced by 1 {total of 2} and the shield gains +5 hardness against the attack {total of +10}
Feat: Deflecting Shield [General/Fighter]
Prereq: 5 ranks in Spellcraft, Shield Expert
You have learned to deflect energy attacks. You can perform a shield block against elemental energy attacks that offer a REF save, like draconic breath weapons, area affect spells, and rays. Additionally, you gain a +5 bonus to the REF save against the attack.
Feat: Improved Deflecting Shield [General/Fighter]
Prereq: Deflecting Shield
You have mastered the deflection of energy attacks. When blocking an energy attack with your shield, the shield gains +10 hardness and you gain a +5 bonus to the REF save against the attack. {total of +10}
This adds a bit of chicken scratch on the side of the character sheet.
Last time through, the idea was picked apart and improved on.. wish I had saved it!