I'm a bag fan of bright effects that disproportionately impact creatures with dark vision. This could be a cool effect for an angels celestial light, basically pushing you to avert your eyes Vs a con save against blindness, with either disadvantage to darkvision creatures or perhaps an alternative effect (change that blindness to disadvantage on ability checks and reserve the blindness for the darkvision having creatures).

I also think the fact that pitch black actually just gives a lot of disadvantage, keeping it to a room or two can be a lot of fun, if used sparingly.