I really like the flavor of this feat, but I am having a hard time finding a way to make the feat investment worthwhile.
The only spells remotely worth spending a feat on are:
Searing Light
Wandering Star Motes
Sunbeam
That would be three feats to get Daylight, Searing Light, Wandering Star Motes, or Sunbeam usable as an SLA, 4/day...
You could even tack on two more feats for Inner Light and Blinding Light... but it seems super situational and may actually never even come up.
The investment is only worth it if you know you will be encountering a significant amount of enemies with light sensitivity or Undead...
The only thing that I can think of that really compliments Heavenly Radiance is the Lantern Bearer/Lighter Ranger's Stunning Light and Paralyzing Light supernatural abilities, which he gets at level 13 and 18, respectively... but all a Lantern Lighter needs is a Glorious weapon, and someone to spam Fear the Sun.
Are there other ways to make Heavenly Radiance worthwhile?