What the title says. It's used as the name of an arc in a xianxia cultivation novel. I'm currently translating it as "Heaven's Profound Light" but that's just me guessing based on what each character means.
Faint Light of Dawn Early Light of Dawn Something like that. You didn't give any details about what it might mean in context with the content of the arc so it's hard to say. But 微曦 means early morning sunlight. 微 here means faint or feeble, weak, not profound. 曦 is morning sunlight.
The final arc is basically about the final battles against the demon sect. That sounds about right though, thank you!