Easiest fix for the entire MNK class is to make GL not stack. If you gained GL1 at lvl 15 GL2 at 35 and GL3 at 50 you can just have 1 stack needed. So at 50 you still get the 21% dmg and 15% atk speed buff you just only have to complete your rotation once to get max benefit from it. This would make it work the same as every other class in the game. It would also keep your dps from being absolute crap for 15 sec while you stack it up. A lot of the fights you have to break off the boss to avoid something or go after an add right as you get GL3 up. Changing up this alone would be a huge QOL fix that wouldn't buff the class at all but still keep the core of it the same.