Blizzard is advising players not to loot their Great Vault until a high priority bug has been fixed, this bug causes loot from the Great Vault to be lower item level than intended.
Blizzard Confirmed – we do indeed have a bug that we’ve not been able to immediately squash. Fixing it is a top priority for us, and at this time, it’s advisable to not loot the Great Vault until it’s been fixed and is offering the correct items. We’ll keep you posted here and on our Warcraftdevs Twitter feed.