User blog comment:Jimeee/Skyrim 1.9 beta update adds Legendary difficulty and raises level cap (Updated Apr 8th)/@comment-83.175.75.92-20130415082354/@comment-122.62.236.49-20130506095710

nothing levels with you past level 50, While 81 is the former maximum, 50 is the master level, Im guessing because it means you have maxed enough skills for a certain playthrough eg. mage