armour +x 'while enchanted'

How does the armour get enchanted? Im not quite sure what it means

It means that if you are enchanted, the armor gets +x armor. It doesn't mean if the armor is enchanted.

Your armor gets a bonus when *you* are enchanted. Since skills have either spell/enchantment/skill/preparation/stance/attack skill/ etc below their description, you can see which ones will work and which ones wont.

Quick example. You get the +5 armor if you cast aura of restoration on yourself, and have the + bonus till 60 second