In addition to the tactical/support upgrades and the armor abilities, Halo 4 also features armor mods for high level players. Passive abilities that will give you some unique traits to improve your efficiency and combat effectiveness in multiplayer.
Each of these armor mods can be unlocked by ranking up to level 10 of the specified specialization. These specialization classes can only be attempted once you have reached level 50. Here is a list of the specializations, the armor mods they unlock and what each of them does.
Operator - Wheelman
Increases the durability of the game’s vehicles in multiplayer and reduces the time that they are disabled when affected by Plasma Pistol bolts.
Wetwork - Stealth
Reduces movement noise, lowers assassination time and makes players less visible in Promethean vision.
Pioneer - Fast Track
Increases the amount of XP earned.
Engineer - Drop Recon
Players are alerted to the position of ordnance drops slightly before they actually happen.
Tracker - Requisition
This mod allows players to reroll ordnance requests for better weapons.
Rogue - Stability
Reduces flinching. Players can maintain their weapon stability even whilst being shot.
Stalker - Nemesis
Gives players a waypoint showing the last enemy that killed them.
Pathfinder - Gunner
Decreases time of overheating on stationary turrets and increases movement speed whilst carrying a detached turret around.