[i]* Loads TX-130 Saber-Tank lazer round*[/i] A guardian can be knocked out, yes ;but not killed unless thier ghost is destroyed and the only way for that to happen is for it to be consumed by darkness. You can say that the ghost can be destroyed by a Spartan, well that is impossible. The ghosts shield is on par if not better than the strength of the Ward of Dawn. Yes it can be destroyed, but by the time the Spartan is able to destroy the ghost, the Guardian would have already been revived. Guardians without the darkness as thier enemy, are immortal from the power of the light