Needler Sentinel
From Halopedia, the Halo wiki
The Needler Sentinel can only be found in the level, Quarantine Zone, playing on any difficulty. There is a lone Sentinel which shoots Needler rounds on the level and, when destroyed, it drops a Needler gun. It can be found on the leftmost side of the first of the glowing orange indoor areas with ruins. Note that this gun is perfectly ordinary, unlike the Scarab Gun.[1] This Sentinel is an oversight from Bungie's tests with Sentinels using different weapons, and was meant to be deleted.[2] This could be because that it would not be logical for Sentinels to acquire Covenant weapons.
It is equipped with Energy shields, and has the same boost ability and flight capabilities that an ordinary Sentinel Major has. The only difference is the Needler rounds it fires.
