Lurking in the "Shadows"

Who exactly are the Shadows?

According to LGpedia: (http://www.lg15.com/lgpedia/index.php?title=Shadow)

"The Shadows are members of the Order who serve as bodyguards for the Elders."

"Shadow members can be distinguished from other people by the omicron tattoo on their forearm. In the center of the omicron lies an upside down tau. "


Here is what the symbol looks like:


"Shadow members are apparently at odds with the Watchers, another branch of the Order, for it was a Watcher that rescued BDJ and eliminated a Shadow member."