Talk:Overlord Volume 9/@comment-42.117.93.110-20150815151454/@comment-26501532-20150818090947

Nah, Ainz said that a similar sword with the same amount of damage cannot hurt him but Gazef's sword can.

So this means that Gazef's sword is more like an armor breaker while other swords can't break through armor. Or Gazef's sword is like a sword that can deal extra specific damage ( such as holy magic) while other swords can't.