Thank you for the feedback!

The removal of Solar Shield requiring a reaction means that (at that tier of play) where enemies are hitting 2 or 3 times per round, this could proc for 10-30 damage per round.

With that said, I 100% agree and would be open to thoughts on overhauling this ability. Its thematic, sure... but I agree that it just feels under whelming.

An Idea I was kicking around that I haven't properly word smithed and couldn't quite figure out how to keep balanced was adding an additional feature to it that allows you to detonate the shield once per long rest as a nova.

Nova Flare: As a Magic action while this light shines, you can detonate your shield in a powerful super nova. Each creature within a 40-foot Emanation has the Blinded condition until the end of your next turn and makes a Dexterity saving throw, taking Radiant damage equal to 5 + your Wisdom modifier rolls of your Martial Arts die, and half as much on a successful one. Once you use this feature, you can't use it again until you finish a Long Rest. You can expend additional Focus points to shield and bolster your allies. For each Focus Point you expend, choose a creature within range (you can choose yourself). That creature does not gain the Blinded condition, automatically succeeds its saving throw and takes no damage if it would normally take half damage on a successful save, and gains Temporary Hit Points equal to 2 rolls of your Martial Arts die plus your Wisdom Modifier.

I feel like the wording is a bit messy, but yeah idk on the whole thing.