My suggestion is a complex one that'll probably push back the release date if it ever gets implemented. Diversify the current skill list. Add different effects and change the damage dealt or the number of damage (like multi shot increasing to 7 per shot instead of 5, bad suggestion but just using it as an example).
And I know people ain't going to like this, but get rid of that whole system where you can only use one combat skill tree. Like you can't use double slash if you have tyberns on. Instead, nerf it so that if you cross use different skill trees, the effect of each skill is cut in half or something. This is a bad way of suggesting a fix, but I think there's a problem with classes not being able to cross use different skill trees. The abuses and imbalances are obvious, hence the reason why I'm skeptical if this will really work.
It's time to make combat a little more interesting
