I do like this but one suggestion, maybe instead of expending on a short rest you instead decrease the damage of attacks with them. It being expended on a short rest feels a bit too gamey in a way, like the armour's healing you, but if you use it in combat it'd feel more like the armours more dampening the blow and taking the force for you. This'd make sense for repairs since there's a limit to the force your armour can withstand before it becomes damaged.

This said this would make it more powerful since it's not a out of combat healing but instead a in combat damage reduction which would make it more useful.