This thread contains a breakdown of the Covenant Weapons’ performances based on the weapons trailer and accompanying Bulletin. Images will be linked to the name of the weapon.
Covenant Weapons trailer
9.19.12 Bulletin
IMPORTANT NOTES
-Aim Assist and Auto Aim decreased, as you will see from images below where the reticle is beside the player and not Red
-All Covenant Weapon projectiles travel faster when wielded by the player than they do when wielded by the Covenant in Campaign
Storm Rifle - First Person View
Type: Automatic Rifle
Range: Close-Medium
Kill Time/Shots: Comparable to Assault Rifle
Ammo Capacity: 100% battery
Breakdown:
-Less Range and Accuracy than AR, but proper timing of overheat yields longer fire time
Covenant Carbine - First Person View; Scope
Type: Semi-Auto Precision Rifle
Range: Medium-Long; 2x zoom
Kill Time/Shots: 7sk
Ammo Capacity: 18 rounds per clip; 54 in reserve
Breakdown:
-Fastest Rate of Fire in the game
-Very accurate
Type: Automatic; Homing
Range: Close-Medium
Kill Time/Shots: 7 needles to supercombine (unconfirmed)
Ammo Capacity: 18 rounds per clip; 22 in reserve (unconfirmed)
Breakdown:
-Needles stick to shields again to supercombine (unlike Reach)
-Reportedly highly effective in Campaign against both Elites and Promethean Knights
-Faster Rate of Fire
Fuel Rod Cannon - First Person View
Type: Anti-Armor Heavy Weapon
Range: Close-Medium
Kill Time/Shots: 2sk
Ammo Capacity: 5 rounds per clip; 10 in reserve
Breakdown:
-Faster projectiles
-“Refined” blast radius
Plasma Pistol - First Person View
Type: Semi-Automatic support sidearm
Range: Medium
Kill Time/Shots: 5 shots to drop shield (unconfirmed)
Ammo Capacity: 100%; charged shot depletes 20%
Breakdown:
-Sustained charge depletes faster than previous games
-Tracking less than previous games at distances
-Faster equip time when switching weapons than others (same as Magnum)
Energy Sword - First Person View
Type: Melee Weapon
Range: Close
Kill Time/Shots: 1 hit kill
Ammo Capacity: 100%; each kill depletes 10%
Breakdown:
-Time between swings decreased (swing faster)
-No more Sword Block
-Less lunge distance
-Getting shot while sprinting with sword will not slow you down
Concussion Rifle - First Person View
Type: Explosive Suppression
Range: Close-Medium
Kill Time/Shots: 4sk (uncomfirmed); 1 body shot
Ammo Capacity: 6 rounds per clip (bulletin says 4 for some reason)
Breakdown:
-Faster projectiles
-Stronger physics impulses from explosions (mongoose launching anyone?)
Beam Rifle - First Person View; Scope
Type: Sniper Rifle
Range: Long
Kill Time/Shots: 2 body shots, 1 headshot
Ammo Capacity: 100% (10 shots)
Breakdown:
-Has moderate Recoil
-Fastest Rate of Fire of the 3 sniper rifles
Gravity Hammer - First Person View (sprinting); held differently while backpedaling
Type: Melee Weapon
Range: Close
Kill Time/Shots: 1 direct hit; splash effect causes damage
Ammo Capacity: 100%; decreases by 8% per swing
Breakdown:
-Faster animations
-Larger area of effect
-More powerful physics impulses
If you have any screenshots to add or any info to correct, please let me know 
-Goat
