First off, I need to say that this is a GREAT SHIELD.  I REALLY LIKE IT THIS THING IS WONDERFUL.  However it does appear to be slightly bugged.

Text on the shield is "Sentinel - This unit's defense is increased by 1 each time they are attacked."

The bug is that it doesn't augment when they are attacked and successfully dodge said attack, the shield's bonus only triggers when they get hit.  I suggest you change the text to say when hit (easy!) or have it work when they also dodge (prob also easy!).

- Manii Names