The M6G Pistol is a typical UNSC sidearm. It fires high explosive bullets with a relatively fast rate of fire and good accuracy. While hardly a sniping weapon, in the hands of a trained marksman the M6G can remain very accurate over long distances.
The Flood (sometimes called The Parasite by the Covenant) is a virulent, parasitic lifeform that thrives by consuming other sentient life of sufficient biomass.
The Flood appears in three primary forms: Infection, Combat, and Carrier, but also can evolve into the 'Gravemind' form that appears to act as a kind of hive-mind for the entire species. All of these forms have an attraction to any calcium-based life form of sufficient mass to accommodate them and will try to attack/infect any they encounter.
NOTE: Calcium? Perhaps they meant "carbon".
When the virulent Flood organism reaches a certain critical mass, it develops a centralized intelligence, which calls itself a Gravemind. This is the Flood personified, and it carries with it the genetic memory of millenia of slumber.
The thing was stopped once before by the Forerunner activation of the Halo weapon, but it will not be stopped this time by a weak alliance of ruined humanity or the deluded obsessions of the Prophet of Truth. The Gravemind intends to achieve its ultimate purpose - to consume and absorb every thinking creature in the Galaxy.
Best considered a kind of airborne infantry, these flying insectile warriors occupy an unusual stratum in the Covenant hierarchy. Drones do not interact with other species except to trade and serve in a military capacity. Their ability to fight on the wing makes them an excellent strategic weapon against ground-based, largely bipedal opponents.
The basic infantry unit of the Covenant, Grunts are dangerous in groups but present little threat individually. Tough, physically strong and capable with a wide range of Covenant hardware, they are a significant military force. However, their discipline is hierarchy reliant and based on the security that comes with strict leadership and strength of numbers. Leaderless, they present significantly less resistance.
Excellent shots, the Jackals seem to be higher in Covenant status if not necessarily rank than the Grunts. They often will be found in defensive positions fighting from behind their distinctive energy sheilds. A well-used shield makes a Jackal a difficult target, but the notch they use to return fire provides a weak spot that can be exploited.
Hunters are incredibly dangerous foes, deployed more like equipment than soldiers. They are brought in by the Covenant for demolition or heavy defense, and always work in pairs. These massive creatures appear to be composed of multiple organisms that exist within the Hunter armor, creating a hive creature in bipedal form. Near-impenetrable armor and a devestating hand-held plasma weapon make Hunter pairs very problematic.
Formerly the ruling military class of the Covenant, the Elites are proud, storied fighters with a long and interesting history. Their recent split from the Covenant is based on differences in religious interpretation of the "Great Journey" but the schism runs deeper than that. The Elites have allied with their former Human foes in part because of a deep-seated resentment of the Prophet rule and in part because they actually understand the scale of the Flood problem.
This disgraced Covenant Commander was stripped of his rank and privilege and forced to don the ancient Armor of the Arbiter. Following this traditional Elite custom, a warrior is sent on a final suicide mission to claim great honor in death.
In the pursuit of this mission, the Arbiter discovered that the Covenant's Great Journey was a lie, and subsequently began a civil war that has shaken the foundations of the Covenant. The Arbiter's people, the Elites, have joined humanity's sturggle against the rest of the Covenant.