Some of the colors in the palette look like they have similar values. So I would try changing the contrast and/or luminosity of each color to try to make them more distinct.
Right now the darkest color, which is used for the border, isn't very dark and short of meshes with the rest of knight. Whereas the highlights are extremely bright in comparison to the second most bright color.
Since the knight is wearing metallic armor there should still be quite a bit of contrast between highlights and midtones, but it seems a bit overdone in this case.

Here's some similar knights (by Cyangmou) that might help as a reference: