Basically a mod that makes it so that when you make a skill 'Legendary' you get a buff to that skill so that attack skills like one/two handed and archery skill trees don't become useless when made 'Legendary'.
For example, if you make your archery skill legendary you get a 100 buff to archery so its like you actually mastered it.
In addition, a change to the perk requirements so that when you mastered the tree you can pretty much grab any perk you want within that tree.