I agree the knight's benefit a lot from NMM. Don't look at all as flat as the metallic guys.
But yes it is difficult and time consuming. I have found that to get a good result I have to go over the area several times with thin layers, adding a little here and smoothing out some colours there.
You can possibly work with slightly thinner paints to make the passages from one colour to the next even more subtle, and perhaps add some even darker shading.
I have also found that a pinch of blue in the grey makes it less dull.
Oh, and you should check the colour balance, cause on this second photo the colours all look quite grey.
Great Start, I'm looking forward to see more from you, when that camera feels like showing up. I hate when cameras disappears, I lost one some years ago, still angry!