Plasma Sword
http://www.yesalbum.com/v001/thepretenders22/plasma_sword.jpg
Summary
The Covenant Plasma Sword or Energy Sword, was thought at first to be purely ceremonial. They are rarely seen in combat, but are invariably carried by high-ranking Elites. In Halo: Combat Evolved, they are first encountered in Truth and Reconciliation, first wielded by a Infiltrator Elite, then by Gold Elites, while in Halo 2, they are optionally used by SpecOps Elites in the first three levels, otherwise the first level in which they will always appear is The Arbiter.
Though it's true functionality is unknown, it seems that the sword's plasma energy is held into a blade-like form with small magnetic field generators built into the handle mechanism. This seems to be a smaller version of the Covenant's capital ship plasma weapon technology which uses massive generators to stabilize, contain, and guide the plasma without interfering with the plasma's effects. If the wielder drops the weapon, a fail-safe activates and deactivates the magnetic field without first dispensing the plasma consuming the handle thus destroying the weapon.
Recent discoveries show that the fail-safe is not always activated, thus Spartans are able to wield the Energy Sword in Halo 2. It also has a new look. Both the "new" and the "old" Energy Swords show through Active Camouflage.
It has a charge of 100 battery units in singleplayer. Varying amounts of energy are taken up by the various means of killing a foe, however normal swipes that merely harm the foe do not consume power. Therefore it may be prudent to hurt a foe until he nears death and finish off with a weapon that has more readily-available ammunition. Around 10 energy is taken by killing a normal opponent, however only 3 energy is used when killing Flood with it.
In multiplayer, there is no limit on the amount of energy the Energy Sword can use before running out. However, like all other "power" weapons, there is always only one Energy Sword on the map in all standard gametypes.
The Energy Sword is one of the very few weapons that can dismember the bodies of dead Combat Forms, preventing their revival by Infection Forms.
Although very powerful, the Energy Sword has been proven through various tests to be completely useless against Hunters, even when slashing at the weakspot.
All yellow elites carry an Energy Sword, and White Elites will pull one out if you get close enough. It will only drop the Sword if it has pulled it out; not if you killed it while it is still using its ranged weapon.
