You can still reduce the brightness by mixing your paints : add a little bit of a darker color (even 1/10th) will do the trick.
If you're afraid of it getting too flashy, applying a thinned down layer of lahmia can mattyfy your painting but
- DO TEST before using it on a completed fig (apply on miniature plastic casing your color sheme, then lahmia half of it, to compare results)
- You can apply lahmia selectively, only on your overbrighten part.
For the unusual color scheme, I've painted a white DE army, with touches of red and blue.
Currently working on a proper website to display them, but you can still check my avatar for now to have an idea :p
If you're interested I can post a couple more pics