I painted Sicarius a few months back, but I never bothered putting up pictures. Of course, when I do bother taking pictures, some jackass grabs it and asks what it is, and breaks the banner off... which is why the second picture is missing the back banner. I took it at an angle where the head covers the chip on the backpack from where the banner got snapped off-- it's easy enough to reglue, but grr. The entire model was done with Reaper Master Series triads, which requires a lot of mixing. You can probably do something similar with GW paint, as long as you thin it down a lot... if you did it with GW paint, it'd be roughly a 75/25 mix of Regal and Ultramarines blue for the basecoat, a 50/50 Regal and Ultramarines Blue highlight worked up to pure Ultramarines blue, then a 75/25 mix of Ultramarines and Ice Blue.