The ArchMage Sin's

Humanity has finally win the war against the demon race.with the help of twelve Arch-Mage. after the war end a few of the Arch-Mages leave.... leaving only a few of the Arch-Mages behind Ethan one of the Arch-Mages that help the wars.however there's something uniqe about Ethan .That is because Ethan can uses his Sin's to expand and regenerate his mana. but what crime did Ethan does to have so much Sin's to empower his mana .Surely he is related to the twelve Arch-Mages and what the twelve Arch-Mages originally does?