If you want to seriously crit Square Enix's Dark Knight it'll probably be tough. There are so many elements playing in the sprite. I think in general most FFT spriters on here and else where hated the Dark Knight, I don't totally hate it but I don't love it either. I think it looks like Vivi killed Steiner and stole his armor lol.
So I'll try to be neutral and hold back any personal feelings about the DK, the colors you chose Rfh are pretty decent. Its not too saturated. I think the yellows need to be changed since its not complimentry to teal, since red is green's opposite and orange is blues (green + blue = teal) I think a dark orange should be used (red + orange). Your call though. I have a feeling judging by the eyes you recolored this by hand and I'm wondering why? You can easily recolor with Palette Editor, so fast you'll be amazed. How did the eyes become teal?