Sword of Bahamut (3.5e Equipment)
From D&D Wiki
Sword of Bahamut
"It fell. It's head on the ground near it, its body coverd in blood. I cleaned my weapon and offerd thanks to Bahamut for another victory over Tiamat, and then left the red dragon's body there, with the other 6..."-A passage from the diary of Lord Owin Temnip
This +6 Bane all evil dragons Greatsword was forged from the fire of Bahamut and the hammer of Moradin for the purpose of killing the evil dragons. It's said that if one of good dragon blood or a Paonil wields it, then its true potentional will show. This is true. If a Good Half-dragon, a Good dragon in humanoid form, a Dragonborn, or a Paonil wields the blade it becomes a +8 Evil dragon smiting Greatsword. This works like this; once per a day the wielder can speak a key word, Bahamut, and for 4d4 rounds if they break the armor class of any one with evil dragon blood, instead of dealing damage they instantly kill that person.