Sadly, no. Armor is equal to half the shifts you get...so 1 in this case.
Armor wearable by everyone.
p279, "The strength of an enchanted item may be reduced by one to make it usable by someone other than the caster, such as a magically armored coat that anyone can wear."
From my understanding, that means you'd
only halve it if others could use it. I suppose the item in question could only be powered by being in contact with it's creator's magical aura, so those other than the creator who try to wear it would get none of the benefits.
I'm considering just metal and maybe electricity(Air or Earth-based) and spirit(the electromagnetism would be magical in nature after, but I see no reason it would deflect/impede a direct Earth, Wind, Fire, or Air attack). And since it would only work for the creator when using it, maybe only work while he was wearing it (to counter the effect it would have on other things nearby) maybe even require a charge time (like at least 5 minutes after putting on)?
Maybe I should just downgrade it to a multi-use item, I could get rid of my extra Enchanted Items slots that way... Enchanted shield/armor type items are giving me a headache.