Here's a model that I made out of various plastic bits that I found lying around. His body and arms come from a Frostgrave plastic demon. I used green stuff to give him boots, instead of the bare feet that the model originally had.
His sword-blade came from an old skaven, I think, and his head is off some old plastic space Nazi. I really can't remember how I got either of those parts. I can only assume that they were part of a sale of random bits.
I painted him black and painted his blade to look like glowing metal, getting colder towards the end. I doubt that a melting sword would make a very effective weapon - at least not for long, but this is space and anything goes.
Then I attempted to paint a glowing effect on his body, as thrown out by his sword. It was not easy, and I found it very hard to work out whether I'd got it right. I think it's broadly correct, but it's very hard to tell if I got it entirely right. Object Source Lighting isn't a technique that I use often, and I'm not planning to do it again in the near future. Still, it was an interesting challenge.