All criticism and hype notwithstanding, Destiny has released, and it has managed to garner a pretty healthy community of players around it. The game, which is centered on the process of leveling up and finding good loot, would, however, be devastated and undermined if one of its mechanics was compromised. Such as, you know, leveling up. And as it turns out, there is one such Destiny bug that makes it impossible for players to level up past a certain point, because of a bugged material.
The good news is, this only affects Hunters who buy armor from the Future War Cult faction. It appears that in order to upgrade these respective pieces of armor, players need Ascendant Motes. Unfortunately, as anyone who has played Destiny knows, there is no such thing- there are lots of shards, but there are no motes.
Bungie confirmed that this was a bug on Reddit, and that they are working to fix it, but in the meanwhile, you are best off not buying any equipment from the Future War Cult.