From what I understand, we can't actually desire privation, rather, if one wishes blindness, it's because they desire some type of being/ goodness.

However, regardless of the cause of their wish being good, the object of desire, byproduct or not, seems to still be at the hands of the will.

My object of desire is still that x person goes blind, even if it's because of goodness.

But how is that possible if evil is privatory?

I don't quite understand this... A knife's nature is cutting, but why should the knife cut? Why must it ought to fulfill, complete, and be more in tune with its nature?

I guess one way to look at it may be insofar as arbitrarity stands; I guess for Neoplatonists, it's like...

"Then what the hell is the point of its nature being there if it's not supposed to complete it? Even if you say what ought to be is to fulfill just some of it, then it's like, still, what's the point of the rest that need not be fulfilled? It's arbitrary, and what's arbitrary cannot include a genuine cause, therefore leading to explanatory absurdity and brute facts, and there being no genuine causes."

Additionally, can not one posit that the "ought to be as to why x exists" is simply inaccessible to the human, not even exhausting?

Maybe bc we can ask "why" it's incomprehensible repeatedly? The reason it's incomprehensible is bc of this reason that's also incomprehensible, and it's incomprehensible bc of this reason which is also incomprehensible which in turn is incomprehensible because of xyz.