An updated and refined method to achieve a red glow effect in place of the usual blue Adeptus Astartes power sword style.
Basecoat the blade Leadbelcher or a silver of your choice. I'd probably give a thin coat of Stormhost Silver now as well, to brighten the glow.
Glaze several thin layers of Mephiston Red towards the source of the glow. Build up layers closer and closer
If you want lightning streaks, draw jagged random patterns with Mephiston Red .
Within the Mephiston Red layer, glaze Evil Sunz Scarlet and then Wild Rider Red . Getting closer and closer on each layer to the source. Paint within the lines of the lightning at this stage, leaving previous colours showing.
At this stage, line in Wild Rider Red around the source specifically, and in any joins/recesses.
Do the same with Fire Dragon Bright , but very fine at his point. Use this to dot highlight where the lightning pattern intersects.
Add a very fine, final line with Yriel Yellow . I also added fine dots in the recesses or perceived hottest points / source as well as a tiny dot over the intersects on the lightning.
Add a final dot of White Scar on the hottest part.
Glaze the whole blade with Contrast Medium with a tiny dot of Flesh Tearers Red . This can be repeated a couple of times over the visible Mephiston Red bits where they meet the blade to smooth transitions.
Shade the blade with thinned Black Templar , pulling towards one direction (see picture). This can take a couple of layers.
Highlight the blade edges with Stormhost Silver . You can also dot on scratches, and if you paint around the lightning sparingly it can help emphasise the effect.