Beam Rifle
Magazine Size: 18
Dual-Wieldable: No
Although you can't dual wield this two-handed particle Beam Rifle, you can zoom (and zoom in again to get an even closer shot) on enemies when delivering their doom. Two bullets fired through an enemy's flesh will knock them over permanently, but you'll still need to nail them in the dome if you want them to die with one shot. The Beam Rifle is similar to the Sniper Rifle in terms of what it takes to slay with it--the difference between the two being that the Beam Rifle fires faster that the human version of this gun.
Pros: You can put down an enemy by shooting at them with the Rifle only a couple of times. The Beam Rifle also pumps out its rounds relatively fast for a sniper rifle. If you're decent at sniping, it is also quite deadly when used during multiplayer matches.
Cons: This Covenant rifle isn't ideal for close range combat, and its slow rate of fire makes it not the best choice when having to kill off a large horde of enemies.
Carbine
Magazine Size: 36
Dual-Wieldable: No
An essential firearm for the Halo marksman, the Carbine is a common favorite among players who want a little more power and distance than your spawning weapon. The Carbine is ever-so-slightly improved since Halo 2, in both firing speed and the damage it causes to others once you pump its rounds into them. It takes several hits to slay enemies with the Carbine, but again, the bullets spray out of this thing fast.
Pros: Overall, the Covenant Carbine very similar to its Halo 2 predecessor and excels at medium-range shootouts. If you're good at sniping enemies dead, then the Covenant Carbine is a great choice to pick off enemies that aren't right in front of you.
Cons: While it is tempting to try to take on enemies who are so far away from you that they are barely visible, the Carbine is not a sniper rifle and you won't be able to kill enemies in the distance.
Energy Sword
Magazine Size: 10 Uses
Dual-Wieldable: No
It may look just like a pointy shard of ice, but the Covenant Energy Sword is easily one of the most devastating weapons available in the game--gripping this ultra-sharp sword in your mitts will allow you to lunge forward and slash through an enemy's flesh quickly. This behemoth blade is different from Halo 2 in that you can no longer slay a hundred enemies with it because the Energy Sword now has a battery life which drains will each Spartan you slaughter. Keep in mind that they are scarce, and if you know where one is you should head for it and try to keep Energy Sword horders for racking up their kill counts by making it hard for them to continuously wield one. If you're equipped with anything less powerful than a Rocket Launcher, Sniper Rifle (or their equivalents), then it might be a good idea to just run when faced with an opponent carrying one of these.
Pros: Insanely deadly, the Energy Sword is one of the worst things to see in your enemy's hand during a multiplayer match. You can also wipe out a significant amount of enemies with it because it is good for many strikes.
Cons: It's a sword, so there's no bullets in it... meaning, you're going to have to be close enough to smell your enemies' B.O. to be able to chop them to death with the Energy Sword.
Fuel Rod Gun
Magazine Size: 5
Dual-Wieldable: No
The gargantuan Covenant FRG nearly takes up the entire screen, blocking a good chunk of what you can see in the game, but its anti-vehicle properties make it the perfect weapon to stop enemies who think they are safe inside a vehicle. If you find yourself near one or more enemy vehicles, just whip it out and blast your targets with its radioactive rods.
Pros: The damage the Fuel Rod Gun deals is extremely high.
Cons: The FRG's projectiles come out slow and if you're faced with several enemies you're going to have a hard time ridding the area of them with this cannon.
Needler
Magazine Size: 20
Dual-Wieldable: No
This gun fires a stream of razor-sharp spikes that can tear through your enemies like a white-hot chainsaw through butter. The Needler may be the stupidest looking weapon in the game, but the it can definitely get you through some of the nastiest battles Halo 3 campaign has to offer. It's also not a bad weapon to use to brutalize enemies during multiplayer matches.
Pros: Believe it or not, the new-and-improved Needler is one of the most powerful weapons in Halo 3. Its rapid firing rate and enemy-seeking projectiles can quickly rip through one enemy in medium-to-long range combat.
Cons: The Needler is no longer dual-wieldable like it was in Halo 2, and it suffers from a small ammo clip. But you should note that wasting an enemy can be done before you even burn through a single clip if your aiming is dead right. It also looks you're holding a robot porcupine in your hand rather than a deadly alien gun when holding the Needler.
Plasma Cannon
Magazine Size: Infinite While Mounted to Tripod / 200 While Not Mounted
Dual-Wieldable: No
The Type-52 Automatic Plasma Cannon is the Covenant version of the Chaingun that you can use to massacre a large horde of baddies. It fires an unlimited amount of plasma projectiles when mounted, and once you tear it free from its tripod base you can carry it with you and continue to destroy your opponents.
Pros: The Plasma Cannon doesn't need to reload-meaning that you can blast enemies to death in an area until there is no one left standing.
Cons: Turning around while holding this heavy ******* is a real pain in the neck and is not recommended. Wielding the Plasma Cannon also makes you move slower than a morbidly obese snail that smokes, so you'll be screwed if you have it and you have a large distance to travel to get to the next area.
Plasma Grenades
Magazine Size: N/A - (You can hold 2 of each type of grenade at once)
Dual-Wieldable: No
Covenant hand grenades are essential in ridding an area of infantry. Once you chuck a Plasma Grenade at an enemy and hit them you'll notice that it sticks to them--it's similar to the Spike Grenades, but unlike the Brute Grenades it does not stick to surfaces or anything other than living targets. The Plasma Grenade is yet another deadly explosive in your arsenal that you should take full advantage of. This infamous sticky grenade, which can be used similarly to the Spike Grenade to gain instant kills, hasn't changed much since Halo 2, save for the new cornea-frying special effects. Plasma Grenades also emit a high-pitched whine just prior to explosion, so move out of the way quickly if you hear one about to blow.
Pros: The Plasma Grenades are exceedingly deadly and they are a good way to kill of your enemies in between loading your weapons (and they'll save your life if you run out of ammunition entirely).
Cons: You can no longer hold 4 of these at a time, so you need to be accurate and stingy when using Plasma Grenades to blow up your foes.
Plasma Pistol
Magazine Size: 100
Dual-Wieldable: Yes
While it does not inflict half the damage of most of the weapons in Halo 3, the Covenant Plasma Pistol is an indispensable weapon to use in the game. In H3, the controversial Plasma Pistol has been toned down in two ways: your battery life now leaks away while you overcharge, and overcharged shots do not follow enemies as they did in the previous Halo game. The trajectory of Plasma Pistol ammunition only tags what's directly in front of you. The good side about wrapping your fingers around this Covenant weapon is that an overcharged shot with it will freeze a moving vehicle, temporarily disabling it. In most situations the Plasma Pistol is not recommended for combat unless you plan on dual wielding.
Pros: It can deplete shields quickly, giving you the perfect opportunity to switch to another weapon to go for the kill. A charged shot with the Plasma Pistol will also disable vehicles. This is a great way to take revenge on vehicle hogs.
Cons: When not used with other weapons, the Plasma Pistol is useless in many scenarios in the game.
Plasma Rifle
Magazine Size: 100
Dual-Wieldable: Yes
Flashy new particle effects and a slightly faster melee attack don't change what is fundamentally a shield-draining weapon, but it's not a complete waste of time to pick up this weapon. Bursts of ammo from the Plasma Rifle are spewed out of this gun at a rapid pace, which is good for fast moving enemies (and also good if your aiming is poor). Harness the Covenant weapon's killing power by holding two of them at a time, to ensure that you can finish them off without switching to another weapon.
Pros: For a weapon that has as high of a rate of fire as the Plasma Rifle does, the damage it is capable of is considerably high.
Cons: It overheats. The Plasma Rifle range is not very high and in many instances it won't be enough to destroy your enemies.