Wow, talk about being missed! :D
I'm very flattered, but you guys were doing fine without me!
However, I do have some comments to make (SPOILERS for Siege at Blue Mountain and Kings of the Broken Wheel):
Rayek is extremely complex, and this whole issue is complex as a result. I have recently decided (partly through the "Two Choices" fanfic I've been writing) that Rayek's real problem wasn't pride, arrogance, or even selfishness-- though they did play a part. The thing that really caused the trouble was what he believed about other elves.
From the first time we see him, Rayek makes it clear that he thinks some elves (namely, himself, and probably Sun-Toucher, Leetah and Savah) are better than other elves. And, to take it further, Sun Villagers are inherently superior to the savage Wolfriders.
In the desert, after losing his challenge, Rayek learns some humility: he learns he was a big fish in a small pond, that he is capable of being wrong and in fact has been wrong about some things, and that he still has much to learn. Then he meets Ekuar, and learns to subordinate his own desires for the greater good for all elves. But he still thinks some elves are superior to others-- witness the way he treats the Go-Backs, and Kahvi ("It shows.") But he still thinks all elves can be raised up-- and he wants to achieve that goal above all else. I don't really agree with Luna that he'd learned any self-restraint (if self-restraint is defined as holding back from what he really wants in light of what others want)-- simply that he'd learned a little humility and perspective.
But not enough. He meets Winnowill, and as Luna said, she reinforces his beliefs. He still disagrees with her: "I had meant to win the Gliders to my cause, not control them as you have done." But then she convinces him that the "rebirth" of elfkind (through becoming like the High Ones once again) is worth even controlling the Gliders for. He willingly goes into the trance to help subordinate them to Winnowill's will. Later, however, he shrinks back from controlling the Gliders' spirits within him, telling Treestump, "I want to help our kind, not dominate them!" And Treestump asks him if he knows the difference-- to which, interestingly enough, he does not reply.
He then drives the Go-Backs from their lodge. It seems as if he suddenly puts the two beliefs together-- that some elves are inferior, but that elves should not be dominated-- and determines that if the elves are inferior/unworthy, it is ok to force and dominate them.
As he goes along, his vision seems to gain more and more control of his thinking-- and Winnowill's temptation from under the sea certainly enforces his idea that he is a superior being who should impose on others what is best for them-- and he goes off on his mission to rescue the High Ones. He gradually moves to the point where even the elves he believes worthy-- Winnowill, Savah-- must be sacrificed to the vision.
Until Ekuar. Ekuar's leaving wakes him up with a jolt. If Ekuar is willing to be wiped out of existence with the unworthy ones, they must not be so unworthy after all. He had learned once that he could be wrong-- now he realizes that he's been wrong again. And he finally sees that what he has believed is not only wrong, but dangerous-- belief that one elf can be inherently better than another can lead to genocide! That's when he is "broken," and he loses his magic as a result. If he could be so very wrong about this, he doesn't deserve to be one of the powerful ones-- so he subconsciously shuts off his own magic.
But I don't think he ever deliberately set out to dominate and control, as Willowill did. I think he had a vision, that Winnie convinced him it was ok to force that vision on others for their own good-- and he believed that this was especially ok for those elves he deemed inferior. But unlike Winnowill, Rayek never set out to set himself up as lord of all elfkind, or to build himself up a controlling power. And it was this, I think, that redeemed him in the end. He was willing to listen to Ekuar above himself. Winnowill never set anyone above herself-- not even Voll.