It's a great idea (I might steal it), but I think you've not quite got the colours right. For the trim, it's more of a dirty metallic colour than a dirty grey. So perhaps Leadbelcher with a thin highlight of Stormhost Silver, then a pretty heavy wash of Agrax Earthshade, perhaps even two coats of this to dull it down and make it look old. For the armour, That's more of a purpley blue, and you've picked a greenish blue. I'm not sure what to do in terms of using a particular paint for each layer, as I don't really paint like that - I mix and blend paints, sorry. I'd use Vallejo's German Grey with a touch of purple and some blue and highlight up from there, I think. I'd have to do some mixing tests first. The Ice White could work, as long as Baharroth Blue is strong enough. I'd probably use Lothern Blue (or maybe Temple Guard Blue) highlighted with a spot of pure white.
As I say, bloody great idea. I'd love to see how it comes out!
Automatically Appended Next Post: I've been thinking about this, and I reckon the way I would paint that armour is using a grisaille technique. There's a fantastic tutorial on the technique here -
https://massivevoodoo.blogspot.com/2017/01/tutorial-deathwatch-space-marine.html
You basically prime black, then drybrush white over the model, making sure to concentrate this on the areas where the light would hit, so the tops of the shoulders, the upper chest, upturned bits of armour, etc. You can then paint really thinned paint over the top (careful it doesn't pool or run everywhere) and you end up with really weathered, pre-highlighted power armour. You don't have to go as high-end as Roman does in that tutorial - he's a genius - you can literally paint a layer over the top and get a cool tabletop standard. I tried it a month or so ago and got a good-looking miniature painted up in about 30 minutes from start to finish.
