Alright, more thorough power review.

Power: B = 4
Speed: C = 3
Range: C = 3
Persistence: D = 2
Precision: B = 4
Potential: D(S) = 2
Adds up to 18, divide by 6 for the average of all stats
3 = barely C

Mathematically speaking, Helios Rod is a low C-rank. Being able to access incredible A-rank Power at range for 2 hours each day should bump this to B for in-universe purposes, but in-game, it's not guaranteed that Nico's going to be fighting at noon very often at all - a competent enemy will certainly avoid challenging him at this time.
The fact that he can only fight in melee at any other time of day might limit him more than you expect. If you don't mind that, go ahead and keep it - it would line up with his personality - but if you think you might regret having an NA that necessitates getting in someone's face without being blown away on the approach, this is your warning. With a potential stat of D, this weakness is unlikely to get any better with practice.

The full effects of Sun Stoked and Sunsetter aren't perfectly clear to me. Do they boost Nico's own physical abilities, like letting him run faster and lift great weights, or does boosted speed and power mean in the sense of making Helios Rod more responsive and hotter? Both?
And what does greater defense mean - does Nico just get harder to harm? Does his usual regeneration get stronger? Does Helios Rod manifest a forcefield?
And greater precision - does this mean he can more reliably land "critical hits," or that Burning Edge will no longer harm his allies?
Does Burning Edge radiate heat, or does it only burn those who come in contact with the fire?

The bio and personality look alright to me, especially since Bee was willing to pass it.