WUAAARGH
the top line of highlights that hug the outline but is broken up * __ * it's noise and banding at the same time, anti-aa. This piece is way too good to have those kinds of shenanigans going on, they hurt, on the pixel level.
Unify your pixel clusters, give them coherent shape, rather simplify than complicate things (and I can see you're quite familiar with this concept too)
Actually construction and basic shading are obviously your strongest points, and basic anti-alias seems to be something you should improve.
So either get better at that AA or ditch it altogether, it'll make your pieces happy!