From Halopedia, the Halo wiki
Imperials in Mdama's Covenant are veterans of the Human-Covenant War, having served under the Covenant military in the hegemony's prime. As befits of their history of service, they are given slightly higher rank privileges and more durable armor from their Sangheili superiors. As Jul's Covenant faction gained permanence, it is not known if Imperials will keep their status or will be assimilated into the larger Unggoy population.
The harness used by Imperials was also issued to some troops during the Human-Covenant War, and is more resilient than the Unggoy Storm version. The helmet is a heavy armor faceplate which protects the whole face. The methane tank resembles a Balahoan octopoda. The harnesses have been seen in orange, red, green, silver, and blue.
During the Battle of Requiem and the Requiem Campaign, Unggoy Imperials of Jul 'Mdama's Covenant commonly fielded Type-25 plasma pistols and Type-33 Needlers. During the Covenant's final days in October 2558, Unggoy Imperials began to make heavy use of the Type-54D plasma pistol and Type-56D Needler.
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