From Destinypedia, the Destiny wiki
Imperial Guard are an Imperial Cabal variant of the Blood Guard Centurion. They serve as Royal Guard and most often accompany Empress Caiatl as her personal Body Guard such as in Caiatl's proposal of an alliance to the Vanguard Commander Zavala.
Imperial Guard are seen adorning similar armor to that of Blood Guard Centurions with some exceptions. Imperial Guard do not wear the scale sleeving of Blood Guard nor have the extendable wrist sword leaving their arms bare. Their sashes are chainlink chrome scale instead of cloth and wear predominantly blue armor with light grey Imperial markings and Caiatl's sigil emblazoned on their chestpiece.
List of appearances