Would be interesting to see a life skill in equipment modification (As in you yourself do the modifications on equipment, except higher ranks get you better modifications than NPCs). They also may as well make Farming a life skill with higher ranks allowing you to grow more crops or maybe even some rare crops.
Item reparation: at rank 1 you never fail a repair! :D
It'd be nice if they introduced a whole new game mechanic. ie: cobwebs and wool to weaving, ores to refining, ingredients to cooking
Maybe something like......actually they already have everything that comes to mind in the game. They could just make it a lot better.
Potion Mastery? Increases success rates of producing potions and potions restore more than they usually would.
Nx Life skill... at rank F- You spend 1000 nx and get a potion at rank 1- you spend 10,000 and get 10 potions
O wai..... Nexon already has that its called every event they do ^^
Gathering. Kind of irritated that regardless of your dex/production mastery, apples/berries will always drop at the same rate unless it's raining or wednesday QQ
Herding, keeping wild animals still while you plunder them for stuff.