Armor for staffs

I'm pretty sure you can get additional AR from a staff (confirm anyone?) but I was wondering how it is used in combat. Does it apply to all locations, or does it operate like a shield and will only provide the extra protection in the front arc?

Thanks.

I am pretty sure this would act as "shield armor" when there is an AR on a staff.

and i can confirm its possible, i've had 2 staff wrappings that add +4 to armour before.

I have a staff "of shelter" which has a +6ar mod on it.