I doubt it for these reasons: 1) Crota is most likely giant, the sword you thought was Crota's is puny. 2) The sword was said to have killed thousands, but come on, imagine your K/D with that sword in the crucible, you'd be toasted with fusion rifles. 3) The sword is identical to every Hive sword. Ever. You could have easily misplaced it. 4) Dinklebot and the Cryptarchs don't know squat. 5) In the prologue for Sword of Crota's mission it says, "The Warlocks believe" it's there. So totally not confirmed. 6) I don't think a Gaurdian born of light could ever wield something so dark without having their own light drained right out of them. Unless you aren't light and the Traveler is actually dark and evil. I'd imagine the sword having a crazy aura to it.