I've been thinking about the Vanguard and the 3 known classes. I'm starting to think that the Vanguard isn't just a simple Class, I think it's something much bigger than that. I believe the Vanguard may be a elite Guardian, member of a higher form of soldier. Maybe fighting for a greater cause. Something to do maybe with Leveling or some sort of quest to join them. Like the Brotherhood from Fallout (though I've never played so I can't be sure). Upon joining the Vanguard after hitting a certain level or w/e you get special Vanguard Armor and maybe weaponry.