HEY! How about if we have a defensive, shield using build option, but increase the number of feats required and give pure class fighters a little something extra?
New Feat: Shield Mastery
Requirements: Base Attack Bonus 6 or Better, Shield Proficiency, Dodge Feat, Expertise Feat
Use: Automatic
Description: The character has improved the skill of not just clumsily blocking blows with a shield, but using the weight and momentum of the shield to help move in combat: angling the shield to cause the opponent's weapon to slide off, moving the shield into the opponent like an active part of combat, and properly absorbing blows to increase the effectiveness of the shield.
Effect: Whenever the character has a shield equipped*, the character receives a +1 dodge* bonus to armor class. If that character is a Pure Class Fighter, that character also receives Damage Reduction 1/-
New Feat: Greater Shield Mastery
Requirements: Base Attack Bonus 8 or Better, Shield Mastery Feat
Use: Automatic
Description: The character has mastered the use of a shield, making the shield almost a part of her as she fights.
Effect: Whenever the character has a shield equipped*, the character receives an additional +1 dodge* bonus to armor class (total of 2 from both feats together). If that character is a Pure Class Fighter, that character also receives Damage Reduction 2/-
Note that this option increases the feat investment to 4, requires at least 13 Dexterity and 13 Intelligence, and gives pure class fighters a little bit of extra love while still being useful to those who are not pure class fighters.