yeah it looks really cool now. I think only some polishing is left to do.
-colored the sword red (decroded was right that it might be a nice detail and the overall palette benefits from it)
-I removed a lot of the AA from the knight against the background. It will cause trouble if the background is really dark.
-I removed some of the banding at the helmet and the breastplate
-I changed the jaggy shield edge near his shoulder to a 2:1 line
-I straightened the strange looking front edge of the shield (I suppose you want to illustrate some nails, but it doesn't work)
-I changed the shinbone armor with that one from an earlier attempt and polished it a bit (this cluster seems to be more effective)
-I toned down the knees - they seemed to be to bright for my taste.
-I removed some dither of the shield (it rather made texture instead of a gradient)
-I removed the 2 pixels in the shadow (they won't work with background)
I dunno were you want to put the knight (bottom-tile wise). Maybe removing the AA of the shadow would make sense from the game-approach.
However I think there is less which can be improved here without changing the general design, all things I listed are only small details.
I also really like the outcome
P.S.:
to prevent the disjointed look (which decroded pointed out) an steeper angle for the backline might work.