No Weapon
From Halopedia, the Halo wiki
The "No Weapon" trick is very easy, basically it makes you drop the weapon that you have, and if you don't have a secondary weapon, you will have no weapon. This is great to do while shooting a machinam or video and you are acting as the cameraman. This glitch/trick works in both Halo 2 and Halo 3.
How to in Halo 2
- Make sure it's an Oddball, Capture The Flag, or an Assault game.
- You can have only one weapon and that is a Plasma Pistol, no secondary weapon.
- Charge up the Plasma Pistol and walk up to the Oddball, flag, or Bomb.
- Pick up the Oddball, flag, or Bomb while keeping the Plasma Pistol charged.
- Drop the Oddball, flag, or bomb quickly and you should be holding no weapon.
[Halo 2 Tricks: Episode 43 *No Weapon*]
How to in Halo 3
- Start a forge game with at least two players.
- Have one player enter monitor mode and spawn a weapon.
Have player two pick the weapon up and at the same time have player one delete it.(This takes perfect timing but it does work)
- NOTE: even though your weapon is gone you're still in combat pose, you can use the lower your weapon glitch but the game will still think you have a weapon so you will look like you have an invisible weapon. For this reason machinima makers that want realisim should use an Energy Sword.