I would be hesitant on armor switching in combat. Out of combat makes perfect sense to have a "civil ability" buff set for bartering, sneaking/stealing, or even using a different tactic to prep for battle (do we charge in, do we sneak around, do have item spells like teleportation).
In combat I think swapping armor would be too powerful, there are too many armor pieces so switching in combat for any useful AP cost would make you too versatile.
Weapons on the other hand are limited to max of 2 pieces of equipment (left and right hand), if you on top of that only have two sets (with switching limitations like I mentioned before), that's basically a primary and secondary weapon set, which might even have overlap (same shield, different main hand).
