After playing this game since launch and seeing the various iterations of thrall power, I believe what the game really needs is an adjustment to the armor system and also armor penetration on weapons/fittings.
I would suggest the following as a good starting point (obviously would need tested):
Light = 20% DR
Med = 30% DR
Heavy = 40% DR
Next, exceptionally crafted armor and armor kits will add % armor value increase opposed to flat amounts:
Exceptional will add 5%, so that is 21% light, 32% med, and 42% heavy
Flawless would add 10%, (22% light, 33% med, and 44% heavy)
Legendary would add 15%, (23% light, 35% med, and 46% heavy)
Armor kits add 5/10/15% increases, so similar bumps as exceptional and flawless
Bulking armor kit add 20% increase at cost of extra weight
Agility would add armor up to 10% DR at 50 points.
So max damage reduction would be heavy legendary armor with bulking armor kits with 50 in agility at 64% DR
Also, with this change I would cap all armor pen on weapons to a max of 30%, which master kits adding 5% and a straight armor pen kit adding 10%. It should work as a reduction and not a flat value drop. So a max armor pen weapon with a spiked weapon fitting would drop that heavy legendary with bulking kit from 64% to 38% DR. Also, all high armor pen weapons should have lower damage values on average.
Keep in mind that there would need to be player/monster health adjustments, as well as damage adjustments to really balance this change. But I feel the changes I am suggesting to armor and armor pen is a needed catalyst to making this game more balanced.