The combat depth is pretty interesting, just a few issue I have with it, mainly native multi hit weapons. The time to make a single attack is very long because you are doing the animation several times with damage between. This also causes a potentially unwanted increase in damage and AP per turn when combined with high damage boost rings. Making multi hit weapons act like an ability with multiple hits might be a good way to fix the issue of multiplying ap gain.
I took out the current final boss and area(s) with the shankers switchblade(3 hits basic attacks), soul shield, shadow shroud and two bone dusts. Basic attacks yield 15 ap per turn if they hit, have +40% critical rate with that setup. I can heal up and buff my crit rate further without expending a turn, while clearing a few status effects. Then gain it back without using the intended abilities. And since I hsve the soul shield I can use magic to heal between battles for "free". Kiva just takes a side line now and is constantly guarding as a sort of damage spreader/sponge. Enemies even later on right now don't deal enough damage to require more defensive armaments. Stacking offense makes things a lot smoother.
The AP economy is a bit off right now in several ways. It might be better to distribute AP at the beginning of an action rather than upon success to allow for more consistency and control of the gains a bit more. Right now you have weird things like kiva's "slimopolooza" ability costs 35 ap to activate but will gain back 15 ap rendering the total cost 20 AP, I would removing the AP gain, especially with how much mp they gain anyways allows for high flexibility.
Speaking of weird abilities, dragon's gaze doesn't live up to it's cost or name. It only deals slightly more damage than double strike but costs 2.5* as much(I can get 4.5k crits with it vs 2k crits with double strike). Making it deal as much damage as a triple strike with a potentially slightly higher crit rate would make it quite a competitive ability for it's cost using the reckless swing/triple swing as the base metric.
Similarly, precise and elemental slash abilities should probably replace their original versions as a kind of upgraded version, as they are right now, their costs make them not really worth it. Absorb willpower could be an upgraded form of concentration, since concentrations ability priority doesn't matter much and the ap gain between the two is only 10 AP, meaning there is no reason to ever use concentration unless you depleted all of your ap due to a lapse of attention
A good example of an variably useful upgraded version ability would probably be chi recovery/soulcleanse at costs twice as much but provides nearly twice the healing and a few status recoveries as well, but can be overkill at times.
And the final thing, using an instant ability should prevent you from using AP generating abilities for that turn. This is so you can't just cheese things with soul cleanse into absorb willpower gaining back 60% hp+ and being net positive for 10 AP that turn.