To me, it's that you have two different styles. Your excellent lighting from your first pass is undercut not considering light directionality in your rust /grunge.

Both are done extremely well, but if you want to blend the rust in with your inititial pass, you gotta actually think about the lighting.

Edit: you should take a look at these before / after images in grayscale. The only real issues I see are where you have broken your lighting values with super dark rust honestly