This kind of question always dead-ends into this paradox: To conceive of enlightenment as something special—to set it in opposition to delusion (or “endarkenment”, if you prefer) – is just another delusion.
Delusion is simply mistaking our perceptions about the self and the world for reality itself. There is nothing wrong with having the perceptions; they become problematic when they get confused with reality. One of the perceptions that causes the most trouble is the perception of difference, e.g. “This is not That”, or “This is the opposite of That”. Such a perception has its uses, but is not a fundamental property of reality. When we forget that and treat differences as real, that’s a form of delusion.
So any distinction people make between “enlightenment” and “delusion” ultimately has no basis in reality. To someone who actually understands this, it becomes nonsensical to say, “This person is enlightened, but this person isn’t”. So can a person who sees through these distinctions rightly be called “enlightened”? That’s the paradox. In a sense, enlightenment requires letting go of the idea of enlightenment.