J-011-422 was the EC# for a Covenant Jackal. In 2552, this individual participated in the Second Battle of Mombasa, holding the rank of Sniper Jackal. However, he discarded his Particle Beam Rifle for a Needler and a Jackal Point Defense Gauntlet.
According to a historical account, a Jackal of his rank would usually keep its Beam Rifle, and not rely on an energy shield, as to better aim with both hands. It is entirely possible that this is simply a case of mistaken identity, and that J-011-422 was simply a normal infantry jackal that was seen with a sniper unit or had, for whatever reason, stolen sniper-grade armor. It is also possible that its beam rifle ran out of ammunition and it had decided to scavenge a shield and needler to re-arm himself.