Class-2 directed energy cannon

The Class-2 Energy Guns, also referred as Twin Plasma Cannons, are standard weapons mounted on many Covenant vehicles, like the Ghost, Banshee, and Seraph.

Summary
The Twin Plasma Cannons are directed energy weapons capable of firing automatic bursts of superheated plasma (in the 100-250 kW range). They are very powerful weapons against energy shields, but not as effective against flesh. Their major advantage is the cannons' rapid rate of fire: 450 to 600 bolts per minute, making them effective against light armored vehicles and infantry, but not against heavily-armored vehicles.

The plasma cannons use energy from the power core of the vehicle where they are mounted, but one disadvantage is that they cannot be fired while the vehicle's boost is engaged. In addition, the bolts have a stun effect, allowing it to destroy "stronger" vehicles, such as tanks, as they cannot turn fast enough to face the attacker. This, paired with the Ghost's evasive prowess, makes it a common maneuver against all vehicles.

Trivia

 * While boosting in a Ghost or Banshee, you cannot fire the Plasma Cannons because the energy used to fire them is being channeled to the boosters.
 * In Halo: Combat Evolved, the Twin Plasma Cannons fired simultaneously and has the capability of stunning the enemy temporarily, while in Halo 2 and Halo 3, they fire alternatively and lack the stun effect. It should also be noted that the cannons in Halo 2 and Halo 3 are much more accurate during sustained fire.