Tyranny of Dragons
Hazirawn is an intelligent greatsword that has been blackened by centuries of literally being bathed in blood.
Hazirawn was once a lawful good Dragonborn of Bahamut who wielded a powerful sword called Xymor’s Fang, centuries ago during the dragonfall war. He was betrayed by his evil adopted brother Krinsseth (who eventually transformed himself into a lich), and his soul was trapped in Xymor’s Fang.
Krinsseth spent the following centuries trying to corrupt Hazirawn by using him to murder innocents and by keeping him bathed in their blood. He would use detect thoughts to put the last moments of pain into Hazirawn’s mind. Hazirawn however, was incorruptible. It is not known how Krinsseth eventually turned the sword evil, perhaps there is a some semblance of the real Hazirawn still left, buried under centuries of hate.