They’re most like a rogue faction of pirates allied with a few grunts. Why?
The elite we saw is a minor. In the Covenant, minors are not allowed to wield energy swords for religious purposes. That blue elite has an energy sword!
He found it next to the elbow grease and decided to take a shot 
(you are right though)
That’s a good theory actually, and it would follow what was said in Glasslands.