I noticed a significant avoidance and mitigation increase by getting weight under 20.

1200ac (displayed) compared to 1100 is huge when soloing.

Looked up a devpost on modern eq ac computations and apparantly i remembered it incorrectly, the monk ac bonus for staying under weight limit adds mitigation ac. It’s not until you start dropping agility avoidance ac goes down.
The post didn’t cover firing rate of defensive skills so no idea if the skill checks gets weighted, and of course no idea if the calculations here follows the same rulesets.
Been at least 3 major revamps of the melee system that i know of on live (hard cap, soft cap (monk nerf), addition of mod2’s, soft cap revisited (unnerf), added heroic stats)