[InsainArcaneBirdbrain]

I think as it currently is, the immunity is fine based on the cost/reward ratio. To explain this, let me lay out all of these plainly (under the assumption of shine knighting, as shine knights is so horribly inefficient in any realistic scenario).

Opportunity costs:

-Shine knighting is a D rank invocation, meaning that it needs 9m for a 5 turn transformation. This taxes both momentum in a fight to a rather substantial degree given it lacks direct damage. This also taxes 7 talent points you wouldn't use otherwise if this is your only invocation from invo cast protection. This also opens up the vulnerability to silence, as you can't self cleanse silence without breaking the invo, a rather large drawback considering one of the "countered" damage types, dark, has one of the most spammable silences in the game in black bubble.

-The skill mandates you to mainhand a very subpar weapon in shine sword. This means you lose out of 20 swa from 2h, you lose a glove slot (meaning you lose valuable items like palms, ghosthands, idol, shields, etc), and the ability to use any other weapon's potential skill since they require mainland.

-Status is a transformation. This means it can't be used with death knighting, or more importantly, install. This also means you can null the status via requinite, null shell, etc. 

Benefits:

-Light/Dark immunity. This largely affects opposing priests, hexers, and the very rare mage VA. Priests probably lack the most answers to SK out of the three, but it's not unfeasible for them to outlast in FP/healing. Hexers use hybrid scalings + statuses, so they aren't stonewalled as much as you think. 

-Blind aura. Huge or meaningless depending on if you're fighting a Kael or not. As far as balance is concerned, this is more impactful than the immunities as it affects all non-kael setups, though I don't believe the skill is overpowered moreso than blind being too good in certain cases.

-Bonus stats (+5). Not really impactful in the grand scheme of things due to stat scaling. Most of the impact this will have generally is in your crit evade by between 6-10. 



Overall, shine sword not being a cast tool and being a poor weapon for a situationally powerful transformation makes me believe it is fine as is. If shine sword WERE to become a cast tool in the future though, perhaps some justification could be made there. As is, the transformation at best serves as a divine shower/enmas spam detterent which is actually a good thing imo.