Defending: A defending weapon allows the wielder to transfer some or all of the sword’s enhancement bonus to his AC as a bonus that stacks with all others. As a free action, the wielder chooses how to allocate the weapon’s enhancement bonus at the start of his turn before using the weapon, and the effect to AC lasts until his next turn.
Moderate abjuration; CL 8th; Craft Magic Arms and Armor, shield or shield of faith; Price +1 bonus.
描述里没有提到任何需要"攻击"的动作.
当然可能是before using the weapon这里的争议......
毕竟"在使用这武器之前"也可以理解为强调"使用武器之后就不能用自由动作获得AC Bonus", 因此也可以判作即使没攻击一样可以用自由动作获得AC Bonus.