1. Basecoat with Thousand Sons Blue .
2. Paint/glaze half of each side of the blade with Temple Guard Blue .
3. Glaze Gauss Blaster Green toward the tip, furthest from the Thousand Sons Blue .
4. Glaze Incubi Darkness on the opposing side, running in the opposite direction.
5. Enhance this shadow by glazing Abaddon Black towards the tip.
6. Edge highlight carefully with Gauss Blaster Green . I like to add a few scratches to the blade here too.
7. Selectively edge highlight tips and corners with a pure white. If you added scratches to the blade in the last step, add smaller lines or specular highlights to them.

If at any point you are unhappy with how the glazing is going, try switching back to the previous colour and glaze in the opposite direction. You can switch back and forth like this at any point, until you are satisfied.