Changing armor in anyway will be only problematic.
This is main concept of battle in Divinity OS 2, first you have to drop armor, then perma CC your enemies. This stops enemy from CCing you in first turn and you from stoping enemies for taking any action.
In my opinion this armor system is great and I wouldn't like any change to it, as I get use to how it works.
If you got problems on Tactician, it's good. Isn't that why you picked tactician mode to be more challenging?
But armor system - stupid. With this system impossible to play physic+mage.
Nonsense, I play mixed team on Tactician just fine.
Yeah, saying that it's
impossible is nonsense, but it's still much, much easier if you actually go for a fully physical or fully magical team, and go primarily for damage rather than CC.
Mixed teams absolutely suffer due to the armor system, because it's simply easier to prioritize taking down a single form of armor, rather than splitting your effort.
Similarly, CC suffers because the armor system is there at all and because CC usually has long cooldowns and short durations. You're better off going for straight-up pure damage, rarely or never using CC.
It's a boring way to play, but try it and you'll see it's true. The game rewards you for massive over-specialization as a group, rather than going for an asymmetric multi-pronged or mixed assault.