The render looks like it was blurred on the right, not sure if that's what you did to make it blend but makes it look kinda lq. It's a pretty simple sig. The supernova kind of draws my attention away from the focal but I do like the effect is gives off. Try putting some normal lighting with some brushing. In this case it would have looked good on the right above his head.
there's no need for better brushes, work that uses custom brushes is usually crap(hence usually) but people who make good stuff with default are good. for Smudging use the vine brush about 0 spacing and around 30-60 something I forgot the name of. and another setting I forgot the name of and your smudging will be pretty awesome