No Weapon Glitch

The No Weapon Glitch is a glitch present in all games in the Halo Series (excluding Halo Wars and Halo 3: ODST). It allows players to apparently disarm their in-game characters.

Halo: Combat Evolved
The No Weapon Glitch is not as well known in Halo: Combat Evolved's multiplayer, but the process is pretty simple. It works easily on Halo PC, but is harder on Xbox because there is less lag. There are two kinds of No Weapon Glitches in Halo PC: one from the host's perspective and one from the client's perspective.

Multiplayer
To perform the glitch in multiplayer, you need at least one other player to work with. Gather multiple different weapons together in a closed area, like in the Blood Gulch Base. Then, have both you and the other player crouch on the pile of weapons facing each other. Consequently, have both you and your partner tap X (the button you have set for the "Drop Weapon" command) repeatedly over the weapons. This should make you continuously drop and pick up new weapons.

Eventually, you will not be able to drop your weapon. This is due to your weapon "phantoming." All other players in the game will view you as if you had no weapon; the player you performed the glitch with should be similarly unarmed.

If you press Tab, you may switch to your other weapon. The game may automatically switch you to your other weapon after a certain amount of time. If you are a client you will find that you cannot switch back to your original weapon—this is because it no longer exists.

Campaign
The No Weapon glitch is more difficult in Halo: Combat Evolved's Campaign. It involves overloading the map with objects, such as weapons, Grenades, and bodies, so that objects on the map start behaving erratically. Overloading is easiest on the Xbox version in Co-op; simply kill your teammate over and over until their corpses accumulate. With a little luck, you will de-load your weapons. You can also de-load enemies' weapons using this same method.

Observations
If, in Multiplayer, you observe a client who has no weapon, they will assume the animation for having no weapon, like in the first Campaign level, Pillar of Autumn.

However, if you observe a host who has no weapon, they will look very different. The host assumes a phantom weapon stance. They are actually still holding their weapon, but you cannot see it. If they were holding, say, a sniper rifle when they lost their weapon, then their arms will look like they are holding a sniper rifle. They can still shoot and melee with their weapon, and if they switch weapons, you will see a weapon floating in the air where they switched. They can also switch out their "phantomed" weapon for other weapons, changing how they hold their hands in the air.

Multiplayer
In Halo 2, the glitch requires an Oddball and a Plasma Pistol. Find an Oddball, and charge your Plasma Pistol. Walk over the Oddball and pick it up while still charging the Plasma Pistol. If you did it properly, your weapon will have been deleted—your hands will be empty, and no reticule will be present on your HUD. If you come into contact with any weapon, you will automatically pick it up.

Campaign
This can also be done in campaign. The level Outskirts is highly recommended because the Blind skull can be grabbed on any difficulty, or Regret because the Assassins skull is always there, and it's ability will only work on Legendary. First, do the glitch where you hold three of the same weapon with the plasma pistol. Drop your dual wielded one. Switch between your weapons to be sure that you have two plasma pistols. Then go to the level's skull. Do the trick as mentioned above but with both plasma pistols. You should now be holding no weapons, but with the abundance of weapons in campaign it will be very difficult to avoid weapons on the ground so you should carry the level's skull with you so you can redo the glitch.

Observations
This can be used for some fun gametypes if everyone cooperates or can be used for making machinima. Please note, however, that unarmed players using the Spartan II player model can still throw grenades while Elites can't; this is because Elites don't have an animation for performing this action when unarmed.

Halo 3
This glitch can be achieved in Halo 3 as well. It mainly occurs during Custom Games, but it occasionally happens in Matchmaking, often during Capture The Flag battles.

Furthermore, it is possible to mod a gametype so that the default weapon is a support weapon, such as a Flamethrower or a Missile Pod. When starting a match with such a gametype, dropping the item before picking up any other weapons can leave the player unarmed. It is possible to do it in Halo: ODST. However it only works for a second player in co-op.

It can also be done in Forge, but requires at least two players. Have one player go into monitor mode and the other in player mode. Then, find or make a weapon, and get one player to pick it up, and at the same time have the monitor pick it up, and then, get the monitor to delete the weapon. This will make the player pick up a "deleted weapon"

Halo: Reach
It is possible to disarm your character in any game mode in Halo Reach. All you need is a turret (machine gun or plasma turret) and an armor ability. First, rip the turret off of it's stand. Then, walk backwards, jump, melee, AND use your armor ability all at the same time, and you will drop whatever weapon you were holding, as well as the turret. Note that if you were carrying both a primary and a secondary weapon at the time, you will need to perform the glitch twice, once for each weapon. In firefight if you're an Elite and encounter a general weilding a plasma turret you can give him your weapon and you will get the turret, you will need to do this twice but be careful, if you walk over a weapon you will automaticly pick it up. This also works with the Energy sword. If performed correctly, your Spartan or Elite will have no weapon, and they will only be able to throw grenades. Also take note that if you walk over any weapon, you will automatically pick it up, and you will have to repeat the glitch once again to drop it. Crouching with the glitch will make it look like you are holding a weapon, crouching walking will not only give you a gun holding animation but will get rid of your walking animtation, crouching and turning around will have your feet remain stationary, but the legs (from the knee to the waist) will rotate indivualy.

Unfortunately, this glitch only works when the one performing the glitch is the host, although guests of the host can do the glitch as well.

This also works in firefight matchmaking.

Trivia

 * In all the games in the Halo trilogy, the Master Chief is seen weaponless during at least one level in the campaigns until he gets a weapon/ ammo for a weapon he's been given.
 * This glitch is used in Red vs Blue several times when the characters needed to be unarmed.