I recieved a +1 anarchic shortsward of deception as a quest reward which I was estatic about since I am chaotic neutral and though it to be the perfect weapon to use on the Cult of the Six quests. But every cutist i have used it on I get a damage indicator like such...

26 - immune

My understanding was that a chaotic weapon works against lawfully aligned mobs. Is this correct or am I not understanding aligned weapons?