This. I don't understand why you can't anyway. If I can level up a Faction doing PvE stuff then I should be able to buy their shit with Vanguard marks. As it stands now there's 6 vendors but only 1 takes Vanguard marks. That's silly. I said it elsewhere but in my opinion Vanguard vendors should only accept Vanguard marks, Crucible vendors should only accept Crucible marks but the Faction vendors should accept both