In the above image, the Tower Hangar desktop, we can see the New Monarchy symbol on the large red banners. In [url=http://i.imgur.com/nrxV7T6.jpg?1]this image[/url], we can see what looks like a variant of the Dead Orbit symbol emblazoned on another banner. Both these images feature humans, so these faction symbols probably don't represent hostile races. Perhaps they represent the Guardian's version of [url=http://en.wikipedia.org/wiki/Chivalric_order] chivalric orders?[/url] It would fit with the fantasy/medieval themes of Destiny, and the idea of the Guardians being knights.