I would consider a few things regarding weathering:
1) What is the surface underneath the paint? Is it primer, is it composite material, is it Zinc Chromate? Paint your weathering chips with the appropriate color. I would think gray or ZC.
2) Are the repairs already completed? If so, then try different shades of blue and paint them on in rectangular patterns to mimmick same.
3) Is the Valk seeping fluids of any kind? What kinds if so? I'd say use blacks and browns for hydraulic and oil stains.
Just a thought.... Nice work.