I would like an improved system of the “exclusive skill” mechanic. One approach could be to make more skills exclusive, without the need to be at 50 mastery points. Especially all skills with rr come to mind. If these were exclusive balancing would be far more easier.
Another approach would be, to divide the classes in a main class and a sub class. You still can choose two masteries, but some skills are only selectable if the mastery is the designated main class. Perhaps you can only improve the mastery bar of the subclass till a certain degree (lets say 32 points).