A Tertiary equiptment slot is a slot used to house anything other than a primary or secondary weapon. Only one item can be placed in this slot and can include anything from a turret to a grav lift. Some items can be stored for later use and others cannot. I have compiled a list of items that could fall into this category.
Mounted Turret: A turret that has been ripped from its stand.
Mobile Turret: A turret that is stored on the players back and is deployed in any desired location. Has limited ammo and cannot be picked up after being deployed.
Sentry Turret: An automated turret like the one from Halo 3’s campaign. Stronger, however, and very effective as a support weapon. Works until destroyed.
Mobile Teleporter: Two telporter nods placed in any two locations the player desires. One sender and one receiver. Easily destroyed. Effective at fast transport but it is a one way trip only.
EMP Blast: A blast that depletes shields and stuns vehicles. Sent out as a blast directed at a target.
Revive Kit: Akin to the Battlefield 3 revive paddles. Used to revive fallen teammates.
Smoke Device: Violently disperses smoke and jams radar.
Gravity Lift: Nuff Said
Bubble Shield: Nuff Said
Tripmine: A more effective and easily hidden version of the H3 trip mine.
Active Camo: A one time use Camo that is stored upon pick up and used when needed.
Overshield: Immediately activated upon pickup and is only depleted by taking damage.
Bandolier: Allows more ammo to be carried for both primary and secondary weapons.
Mortar Pod: Similar to the missle pod, fires mortar rounds directly forward when being carried, but when holding L is setup to arch mortar rounds high into the air.
Mobile Sniper Tower: a small version of the covenant sniper tower used for only one person.
If you have any questions or ideas please feel free to add to the list. I will update as I go.