Looking good mate. Gave me a crick in my neck while I had to go over the photos, kept seeing nice little details.
Also
OSL is entirely possible to do it with brushes, you just need to be particular with where you apply the paint and how you do it. If you basically consider it like a normal highlight (using paints that are maybe slightly thinner than normal), and work up through the colours all the way to pure white, you will come out good.
I did some tonight on the Volkite blaster of my Tech Priest Dominuns, it was all done with a regular brush. You can see it below.