NOTES: Keep in mind that all the steps of the tutorial where made in the app Procreate, the names of all the layer effects and and actions are part of the base system of the app.
Also, even tho the tutorial was made with a blue/teal color, this effect can de made with any color of your choosing~ this is just a tutorial on how to achieve the effect.
STEP ONE: Make a base drawing to apply the light effect to and decide where the light is going to go. In this case, i chose a power claw and decided that the focal point where the light is going to come from is the tip of the claws.

STEP TWO: Once you’ve decided where the light is coming from paint a color base color of your choosing and a lighter tone of that same color (this one closest to the light source).
Then apply Gaussian Blur to the colors just added, letting it go over other parts of the base drawing.


STEP THREE: Make a Clipping Mask layer over the lineart with a darker tone of the color you’re using and apply Gaussian Blur once again~

STEP FOUR: Duplicate the layer of the blurred colors you just added in step two and move them over the lineart layer of your drawing and change the layer to the blend mode "Add" to make it look shiny.

STEP FIVE: Using even lighter colors and taking advantage of the geometry of the drawing you’re using as the bae of the effect (if it has geometry) add highlights wherever you think the light might hit.

STEP SIX: To add the lightning sparks that 40k power weapons usually have add a layer on top of all the layers you have and (using the dark color used in step three) draw some lightning-like lines.
Then, erase the ends to make them blend into the rest of the drawing.


STEP SEVEN: Duplicate the lighting layer and make them lighter/white, leaving the darker color one one layer behind. Then apply Gaussian Blur once more~

ALL DONE~