Weaponless Elite glitch

The Weaponless Elite Glitch is a glitch which can be done on the Halo 2 levels Metropolis and Gravemind and Halo 3 level The Covenant.

Metropolis
Go to the level Metropolis in Halo 2 and board the Scarab. Throw a plasma grenade at the Scarab operator Elite while he is operating the Scarab. He will make the animation for an Energy Sword but won't have one. Easy is the best difficulty for this.

Gravemind
Get the Catch and Sputnik skulls and go to the level Gravemind. Make sure that the difficulty is on Easy. Go to the first outdoor area past the Hunters where the Honor Guard Elites and the Brutes are fighting. Get the SpecOps Elite toward the right to throw a plasma grenade at you. You should take out the sniper Jackals before attempting. Either shoot a Brute Shot at the Elite's feet or jump above his head, but just enough so he doesn't stick you, to make him throw the plasma grenade up in the air. If you did it correctly, the plasma grenade will land on his head and not you, and he will do the animation for pulling out an Energy Sword. Don't worry, he won't pull one because he's a Special Operations Elite and they aren't scripted to have a secondary weapon. Instead, he will pull out an invisible Energy Sword and will follow you around the Valley of Tears. When you reach the part where the Flood-controlled In Amber Clad comes, he will not follow you across the light bridge but stand there staring at you.

The Covenant
When the Separatist Phantom arrives to pick up the Arbiter, use a Energy Sword to melee and destroy the Plasma Cannon platform. The Elite operator will not take any damage and when he gets off the turret, he will have no weapon. If you stick him with a sticky grenade, he will take out a Energy Sword. If you betray your marine allies, he will attempt to melee you and his melee does deal damage.

Explanation
Because the Elite's grenades are weaker than yours, it will not kill him but will make him do the animation for the Energy Sword, causing him to become "Weaponless".