One thing I definitely agree with--and mostly because it looked like it was going in that direction--is the light/dark fist lore of the job and yes, ShB should've been the perfect opportunity to go into that.

Martial art masters trying to discipline themselves in media/literature is nothing new. Most famous video game example is Ryu from Street Fighter, who constantly is at war with himself to not fall into the temptation of the Satsui no Hado. We could've had something similar or at the very least, trying to continue mastering equilibrium, not just from a lore perspective but gameplay too. I would've liked seeing a "shadow fist" counter where it continues to build up, then you have the choice of sacrificing it or using it, each wielding its own positive effect and drawbacks.

Oh well