#2 - Sept. 26, 2013, 3:11 p.m.
Locking this as it's a duplicate topic, but to answer your question at the same time...
This is actually because of the issue with Conquest caps at the start of the season. Some people were able to purchase the Conquest weapons because they had unnaturally high Conquest caps and to prevent the use of these weapons while we resolved the issue, we changed their level requirement to 91.
I hope that explains this for you and if you wish to discuss this matter further, please do so in the main thread here:
http://eu.battle.net/wow/en/forum/topic/8241264072