@ Bungie Sam
Yes, i know that, but these are beign colored black and blue on purpose. And just for you to know (in case you dont) originaly the knights are blue. And since we know from the Launch Trailer that the Didact makes his first appearance during the third mission, and the Knights are blue on the third mission, and suddenly change to orange in the fourth, this makes me think that the color change is related to the Didact's control over them.