Here's how I would envision it:
When you cast the spell, light flares around your head, and beams at a particular enemy, blinding them with searing light.
After you cast the spell, motes of light remain encircling your head like a crown, and you are masked with the alien psyche of the distant stars. You continue to lash out with this psyche, and, where it caresses the minds of the weak-willed, it burns them from within with dire radiance.
Admittedly, the mechanics are a little borked (I'm surprised they make you roll an attack roll for that piddly damage!), and the flavor text is, as always, basically meaningless. This is me imposing flavor from the outside.