I'm not a fan of lowering the AP cost for sword and board. The shield is a defense/utility item, therefore, we should increase defense/utility not offense. The previous ideas of armor regen and new skills related to shields are great.
Most enemies do more damage than the shield has armor. In essence, your shield is broken and useless in one hit. More armor, %block, armor regen are needed. Fortify costs 1AP, provides more armor, can be cast on anyone, and can be recast for additional armor later.
Utility would also be a great addition. Warfare has many skills designed for 2h in mind, heavy damage output (rage, whirlwind, cripple.) Skills previously mentioned were great. I would love to see a few skills less related to damage and more to battlefield control (stag, stun, taunt, reflect, bunker.) Additionally, adding skills to protect allies would make shields more useful.
In summary... higher defense, not less AP. More utility and control abilities to make you collect aggro, keep it, and make it difficult for enemies to hurt your allies.
