It is a good question, the man says you can not enter the vault of glass alone, he also says no one was with him, but he was not alone! He is a man of mystery, i want to find out more about him, he was some sort of early explore/fighter, with out him no one can raid the vault of glass, the vault of glass is where the vex control time, they do time travel and also morph reality , that is why The Gorgon in the vault of glass( the sneaky part) can look at you and you die, they erase you from time/existence .This Kabr dude made a shield out of one those Gorgons, that is bad ass!