Spoilers! A certain characters eyes

[Morningstar1337]

Just...why the ever loving hell does SE seem so damned determined to cripplingly MAIM the core characters?

Drama. Put simply the Warrior of Light is at Mary Sue levels of competence and power, I'd say that injuring Superman (WITHOUT Kryptonite, mind you) would have more lasting results then directly harming the WoL. But that said, s/he does have a weakness (also one of their strengths), their friends. The Scions are not god-tier god-slayers. They are simply normal human beings, and thus having something bad happen to them would indirectly hurt the WoL on an emotional and strategic level (since they are the people that help them get close enough to the primals lairs), Same principle behind Hauchfaunt's death really (though done to grater effect with him due to presentation)

On top of that, Y'sholta's eyes are really not the issues, the aethersight arguably compensates for that. The real problem is the shortened lifespan, and I don;t think Matoya's crystal of light can help with that (She prolly would have offered to help if that were the case).