One thing I haven't heard mentioned is weapon active abilities. I think their balance is generally a bit out of whack. First off, we know reliable full attack actives are usually why dual wield ends up being strictly better than two handers (there are other factors, such as two handers not quite having the penetration one would expect from them, especially greatsword). Similarly the built-in "no recovery" that guns have is what makes them desirable for a lot of shenanigans that involve spamming skills that take your weapon into account without actually needing to ever reload your weapon. To be perfectly frank, I don't understand why that's a thing. It's fun... for a little while, because you have the satisfaction of having discovered a way to game the system, but when you start reflecting on the implication you realize it makes some entire weapon types more desirable than others for reasons that are frankly pretty stupid. The end result being, what weapon types are actually good have nothing to do with the inherent qualities of that weapon type and everything to do with how abilities behave. That's not really a good thing in my opinion.
The main problem with full attacks in my opinion currently is that, you only ever go through the recovery/reload of one of your weapons if you're dual wielding. This makes full attacks so much better dual wielding instead of 2handing or 1handing that the discussion pretty much ends here. There is no logical reason to not be dual wielding when you plan on using full attack actives, it's pretty much unjustifiable. My question to that is : why not actually make recovery work with full attack the way it actually should. Make the user go through the recovery of each of his active weapons after using it. Force him to reload both guns. That way, there is a cost attached. Dual wielding still amounts to more burst damage from a full attack, but is longer to recover from. 2hander does less damage, but you get to act quicker. 1hander is the quickest and has the highest accuracy, but does the least damage. Simple stuff. There's a kind of dual wield fetishism in the design of both POE games that I think is strongly hurting weapon balance and weapon choice strategy, and it's a real shame.
Second, stuff like evasive fire. Not having inherent weapon recovery / reload tied to it's usage makes absolutely no sense to me. It is pretty cool to have rangers teleport around shooting everything like they're Matrix stunt doubles until they run out of resources, but I can't in good faith say "this is how things should be". The skill should apply the recovery / reload of the equipped weapon imo, it's just silly not to.