Say I'm a ele with base AL 60 and I have these weapons.
Sword +5 Armor
Shield +16 Armor (didn't meet requirement)
Blessed insignia +10 Armor while enchanted. I know I will be enchanted.
The sword and shield add global armor, so you'll have at least 73 on each piece; 60 (armor) +5 (sword) +8 (shield [you only get half when you don't meet the req]) = 73 armor. It gets bumped up to 83 only on the pieces that have the blessed insignia and then only while you're enchanted.