Sniper rifle – 4/12: The sniper rifle is the most accurate UNSC weapon, and it allows you to pick off enemies from very far away with its variable 5 – 10x scope. Even on legendary, the sniper rifle is useful against elites because it can kill them in only 2 headshots. (Elite generals require 4 headshots to kill, so you should use other methods to kill them). Because of its pinpoint accuracy, you can kill elites from so far away that they cannot return fire. The sniper rifle is especially useful for sniping enemies out of turrets because they cannot move to avoid your shots. Whenever possible, I suggest that you snipe elites operating a wraith’s plasma turret so that you can more easily destroy or hijack the wraith.
Spartan laser – plasma/25% per shot: The Spartan laser is one of the highest damaging weapons in the game, but it is also one of the hardest weapons to use. In order to fire the Spartan laser, you must first charge it up by holding down the trigger. After you charge it up for roughly 2 seconds, it fires a powerful, accurate laser. You can use the Spartan laser from a distance because it has a 2x scope and the laser travels infinitely. However, as you charge up the Spartan laser, it creates a smaller targeting laser visible to all enemies. Therefore, infantry can easily avoid the laser, so it is only useful for destroying vehicles. During the campaign 7.62×39 ammo , you only have access to the Spartan laser when you also have access to powerful vehicles (such as a Scorpion or Mantis), so I suggest that you use the vehicles instead.
Sticky detonator – 1/5: The sticky detonator is an evolved version of the grenade launcher from Halo Reach. As implied by the name, the sticky detonator fires grenades that stick to any surface. Once you fire a grenade, press the trigger again to detonate it. The explosion deals a large amount of damage and has a high blast radius (roughly equivalent to 2 frag grenades,) though it has no EMP capabilities like the grenade launcher from Halo Reach. You will have access to the sticky launcher during much of the 7th mission, and I suggest that you use it to combat the hunters you encounter. Step out of cover to fire at the hunters face or back, then return to cover to detonate the grenade. It will take 4 – 5 direct hits to kill a hunter. I do not suggest that you use the sticky detonator when combating any other infantry because a headshot weapon and a plasma pistol provide a much more reliable loadout for fighting covenant. You will never have access to a sticky detonator when fighting Prometheans.
Beam rifle – plasma/10% per shot: The beam rifle is the covenant sniper rifle, and it is by far the most accurate covenant weapon. It deals as much damage as the UNSC sniper rifle, so you can kill most elites with 2 headshots. Just like the sniper rifle, it has a variable 5 – 10x scope, so it allows you to snipe enemies from very far away. I suggest that you use the beam rifle for sniping enemies out of turrets. The beam rifle has much less recoil than the sniper rifle, so it is a lot easier to snap shot enemies (this is when you fire without looking down the scope.)
Jackal snipers are the only infantry that use beam rifles. They can kill you with two body shots or one headshot, though they rarely get headshots. As soon as a sniper hits you once, immediately take cover before he can finish you with a second shot. To kill a jackal sniper wielding a beam rifle, stand in cover so that you are barely exposed but can see his head. Kill him with a headshot with your headshot weapon.
Carbine – 18/72: The carbine is a fast firing, accurate headshot weapon commonly found in covenant areas. The carbine is the fastest firing semi-automatic weapon in the game, though I suggest you fire slowly and carefully to conserve ammo and more easily get headshots. It also has the most spare ammo and ammo per magazine of all of the headshot weapons. For these reasons, the carbine is my favorite headshot weapon for fighting covenant. However, the carbine deals very little damage per shot, so it is terrible against Promethean watchers (though it is great against crawlers.)
Jackal snipers and elites both wield carbines. These enemies usually cannot get a headshot, so they pose little threat. Kill carbine wielding jackal snipers with a headshot. They may shoot you a few times before you can kill them, but your shields can easily absorb this fire. Kill carbine wielding elites up close with a plasma pistol and headshot combination. These elites pose less threat then elites with storm rifles because the carbine deals less damage per second than the storm rifle.
Concussion rifle – 6/18: The concussion rifle is a rapid fire grenade launcher that fires concussion rounds. These rounds detonate on impact, and they deal much less damage and splash damage than the sticky detonator or any type of rocket launcher. When the concussion rounds explode, they knock their target back considerably, so you can stop a charging enemy by bombarding them with concussion rounds. On legendary, the concussion rifle does not deal enough damage to be an effective weapon against any type of enemy.
In the hands of the enemies, the concussion rifle poses a large threat. Only high ranking elites wield the concussion rifle, and they can kill you with 3 – 4 shots. Since concussion rifle rounds travel slowly, it is best to engage these enemies with from a distance. As soon as you come within plasma pistol range of the elite, remove his shields with an overcharged plasma pistol blast and kill him with a headshot before he can approach you. Avoid concussion rifle fire by moving perpendicular to your enemy and jumping often.
Energy sword – plasma/10% per swing: The energy sword is a melee weapon that greatly increases the damage of your melee attack. Not only does it deal enough damage to kill most infantry in 1 or 2 slashes, the energy sword also allows you to lunge at your enemies from over a meter away. I do not suggest that you use the energy sword because it requires you to get very close to your enemies. This leaves you very exposed and can often lead to your death on higher difficulties. Furthermore, it requires 2 slashes to kill most elites, leaving you vulnerable for even longer.
When combating enemies with energy swords, it is vital that you do not allow them to reach you. Elite spec ops most commonly use energy swords, though you may see elite generals, zealots, or even majors using energy swords as well. These elites are always very aggressive and they will charge you nearly as soon as they see you. When you see a charging elite with an energy sword, it is your top priority to kill him before he reaches you. Begin by backing up while you overcharge your plasma pistol. As soon as you overcharge it, immediately fire the EMP blast to remove the elite’s shields. This will usually cause him to stumble or shake his fist, buying you more time. Immediately finish him with a headshot before he reaches you.