-Differentiation between MCH and BRD gameplay, the implementation of GB/WM on both classes (since they are fictionally the same ability).
-The effects of WM on BRD's 2.0 skills, traits and animations (especially the waist-down clipping on windbite and empyreal when you use another oGCD right after)
-The Implementation of MCH and their ammo mechanic.
-Scrapping of "different attachments" and "ammo usage" mechanics for MCH.

These are personally my biggest points of discussion as a former full-time BRD and current MCH main.