I have always, ALWAYS, hated how RPG Maker makes shields only adds to Defense. Makes it that Dual Wield is better 9 times out of 10, because you'd rather kill an enemy instead of taking less damage. (It also never sat right with me how shields needs to be in the way of an attack to block it in contrast of armor who's always on you).
This plugin falls more in line with how I think shields should be normally working. Blocking a significant portion of incoming damage is worth considering not using dual wield.
I'm treating myself to it. These shields are about to become good, mark my words.