Fuel Rod Gun
From Halopedia, the Halo wiki
(PC/Mac Multiplayer Only) Rate of fire: Average (2 round per second) Damage per hit: Very high Range: Medium Accuracy: Low-medium Magazine size: 5 rounds per clip Maximum ammo: 30 rounds
Advantages
The Fuel Rod Gun is the Covenant's answer to the human rocket launcher. In the first Halo, the Fuel Rod fired large blobs of plasma in arcs across large distances, and had no reload mechanism. In the campaign of Halo 1, it was impossible to pick up these weapons from fallen enemies as there were fail-safes that made the weapons self-destruct with the force of a frag grenade. However, in Halo PC, it is available as a weapon in multiplayer. Being an effective suppression weapon, a common tactic in CTF is to bombard the enemy base from afar, most of the time from a position obscured from view. Since the view of the targeted area is obscured due to having to compensate for the arc and having to aim high, it is unlikely to kill a player, but it is intended to at least deal damage to enemies while having the bombardier's teammates finish them off.
In Halo 2, the Fuel Rod Gun was replaced with the similar Fuel Rod Cannon. There were no fail-safes, allowing the player to pick up the weapon. It is magazine fed (so is the Fuel Rod Gun in story background but for the game, when used up it is discarded), with each cartridge holding five rounds. The gun fires fairly fast, and reloads at around the same rate as the rocket launcher. Another addition to the Fuel Rod Cannon was the 2X scope, allowing precision firing. Another noticable difference to the Fuel Rod Gun is that it is a different color, the Fuel Rod Gun is purple while the Fuel Rod Cannon is a brown color.
The high ammo capacity, rate of fire, and damage of the Fuel Rod Gun/Fuel Rod Cannon makes it a force to be reckoned with.
Disadvantages
The Fuel Rod Gun/Fuel Rod Cannon does not have a tracking device, and the projectiles are slow. It also takes many shots to kill someone. It is still capable of killing a user at short range, and ammo will run dry quickly in Legendary. The large size will often obscure your vision, making it harder to see who's there to kill you. Unfortunately, in Halo 2, this weapon is not featured in Multiplayer.
Hunter
There are the ones that the Hunters use which shoot out long beams of fuel rod. In Halo: The Flood, it is revealed that, like all other plasma weapons, the fuel rod gun can also overheat. So far there isn't a way to take the Weapon after killing a Hunter(but you can pick it up in the CMT Halo: Custom Edition Campaign Mod after killing a hunter; there isn't a FP model and it is very hard to aim, however).
SpecOps Grunts
The fuel rod gun is also carried on the shoulders of many SpecOps Grunts, although Major Grunts were seen once wielding them in the level Two Betrayals. The grunt version of the Fuel Rod Gun fires a powerful blast of plasma that's fired in an arc and capable of exploding like a mortar.
