First of all, I would like to thank you for this great opportunity to work together with the community on balancing!
I think it's good that you are aware of the topic and want to treat it as well.
Although I find the potential change in set skills good, I wonder if changing or replacing some set-skills will adequately capture the complex topic of balancing.
Fundamental class differences can certainly be remedied well, but I wonder to what extent such class differences prevail at all seriously.
Classes which are actually balanced in my opinion are: druid, scout, priest, champ, knight, warlock, warden and rogue. In my opinion, global class inequalities are reduced to the magician, who cannot keep up with other classes in damage. Surely you can argue with the other classes, whether one or the other is stronger or worse, and possibly there may have a small adjustment also have positive effects.
I think much more decisive is currently not the damage done to the different classes, but the disadvantage that close combatants die much faster because of damage to the surface than as far-fliers. Perhaps this could be counteracted by adding a set-skill similar to the weapon master of the warrior for these classes, which would reduce the area damage suffered.
However, most of the necessary balancing is in the different secondary classes of the different classes. Because while now you can actually play any class with one or more secondary classes meaningful, there are some class combinations that are not useful because their skills are not adapted or too weak.
Therefore, I would be very happy if this problem is also treated. Maybe only after the set skills, if that would be too much at the same time. Nevertheless, this aspect should also be considered during the set-skills balancing so that no aggravations occur, also with regard to the different class combinations.