I'm making a reach build which doesn't always attack with a weapon on his turn, however I want to threaten and attack still. How does this work with a buckler?
If I read it right, it means that until I take an attack I still benefit from the buckler, but when I make an attack of opportunity with my glaive, then I my shield bonus until the beginning of my next turn.
I would say that you would retain the AC bonus up until the point when you actually make an AoO. Here's why:
The buckler states that you can wield a weapon in your off-hand but that you take a -1 to attacks with the weapon. It does not indicate that you lose the AC bonus until you use the weapon.
Based on SKR's logic regarding the defensive weapon property, 'use' in this case means that you've actually made an attack with the weapon.