The name The Black Guard was given to a leaked group of specops soldiers discovered in financial documents to be under the control of Section M.
Although nothing concrete has come forth, some of the tech rumored to be Black Guard hands includes a gun that fires a pulse of energy that can melt steel, a neuraldisrupter weapon that causes temporary paralysis, and light-warping material that can achieve semi-invisiblity in free space. It is only a fraction of the weaponary they're supposed to pack. They have a wide range of defensive gear as well, like powerful ABW Filters, Energy Dampeners, and a highly effective variant of Impact Gel.
Although it is unknow what they do actually have, it can be garunteed to be advanced.
Although virtually nothing is known about their practices, rumors are awash in the Aug community. The most common one being that they come with little warning and make the Augs "go away." They've become some kind of Boogy Man for the Aug community.
No one has seen Black Guardsmen operating before, which leads some to believe that, if they do exist, they work on some unprecidented level of stealth. If all the rumors are to be believed, then the evidence suggests the Black Guard are brutally efficent and well versed in Aug combat.
There has never been a report of someone being targeted by the Guard and escaping.