Hey..sorry to say this but.your theory is inconclusive..in anything in history when there is three of the legendary swords together.the fourth must also be there. Explanation? Sure. Joyeuse, cortana and durandal are all legendary swords. The fourth is Excalibur. So when there are three A.Is all named after legendary swords that there are FOUR of. There's gonna be another A.I. Either in destiny or another game bungie will make.