To be fair, Armored is an On/Off ability.  If the damage is less than 6, then the attack is negated.  If it's 7 or more, then the Knight takes the full damage.  Now, if you were to reduce<em>every</em>attack by 6 damage, that might be broken.<br/><br/>And, as always, it only works against<em>physical</em>attacks.  It doesn't work against Magic.