Cloak of Shadows def bonus question

[LavCat]

2): Find the item defense of a character. This is the sum of all defense you obtain from items, which includes your helm, armor, shield, gloves, belts, and boots.

I am planning a barbarian to use Ribcracker for mid-career. I have a question about what goes into this item defense. On an item of armor is +def applied before +%def? In other words would the bonus of an ivory jewel be applied before the +% bonus of the armor?

And speaking of Ribcracker, it is a mace for purposes of mastery is it not?

Thanks!


Edit: spelling, of course.