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?
I play with friend on tactician.
We have not problems. Really not problems - game is so easy. I install mod for more difficulty. Act 5.
But armor system - stupid. With this system impossible to play physic+mage.
Need really rework it.
The best way, i think - add armor+magicarmor amounts to HP, and make skills damage through armors types, damaging both of hp and armor.
It will be the best system.