Something that would be cool for an expansion would be classtrees.
A class tree works like the current weapontrees but is the combination of 2 weapons.
So if you use GA and Sword n Shield you would have a Heavy Tank class tree where you can unlock 3 class skills…
If you use Firestaff/Ice gauntlet you get the Elementarist class tree and so on…
This would open up some great balancing options… the heavy tank build could get a skill break stun/root or something
The elementarist could get blink…
Something like this…