Hi.
I has faced with the strange situation (seems like bug) related to crafted item with UV.
My crafted shield (UV Shadow MAX!):
http://i53.tinypic.com/156r68g.png
I was confused by length of the shadow bar, because I have seen in the Auction House an item with the lesser UV (High), but its bar was longer:
http://i55.tinypic.com/25jyu8g.png
Then I searched more in the AH and has found that the length of UV bar of my item is equal to one with the UV Medium:
http://i53.tinypic.com/2vani4i.png
So, my shield seems has an incomplete defence bar. Its length is equal to one third of prescribed (like UV of 2nd level, but not 6th). =\
You are comparing a shield to armor and helm. That is like comparing apples to oranges. You have reached the "maximum!" shadow resist on a shield, which is different then it is for armors and helms. It is probably related to things like stat-budgets on gears.