Ok so then Kellhus is "special" - weaker than the rest because a stick confused him.
How do you know that the same would not have happened to any other Dunyain? How do you know that Moenghus wasn't overwhelmed when he first left?
Agreed.
He went out into the woods, in the winter, without a coat and without knowledge of foraging, hunting, or trapping, without knowing where he was going.
Arrogant. Hubris. Idiotic.
He went out the way he was sent; if he didn't have any survival skills, it is because the Dunyain didn't teach him any - it is doubtful whether the Dunyain themselves had any to begin with.
Some of the brilliant things that Kellhus gets himself into in 2 books:
Nearly dies from exposure, finds a ruined city for shelter just before he passes out.
Nearly dies again from exposure and hunger, he is saved by Leweth.
He goes to Atrithau, does some standard mindtricks and gets a little band to go south, nearly dies by sranc attack.
Gets rescued just as he nearly dies from blood loss by guy who randomly showed up.
Fails to see Moenghus' condition path in Cnaiur, screws that whole thing up and creates a lifelong enemy that nearly kills him several times.
Goes to the Holy War, nearly gets killed/captured again, randomly saved by random events again.
Joins holy war, finds Achamian, gets lucky that he's a skeptic and doesn't report him to the Mandate.
Gets lucky at the first battle, says some random stuff that magically makes things work out.
Nearly dies on the circumfix (his own admission - he doesn't know how he's going to survive), saved by crazy lunatic.
Nothing to imply that any other Dunyain would've fared better - Moenghus himself had been taken captive by the Sranc, and only just survived. He led himself to dead ends twice - first by scarring his arms, that made going to the Nansur impossible, and secondly by blinding himself. And I am going to go out on a limb and assume dying was not a part of his plan, so ultimately, he failed far more spectacularly than Kellhus. The failings of Kellhus could easily be the failings of any other Dunyain - in fact, other Dunyain could fail way worse than he did. He went against great odds and ultimately he came out on top (at least until the second series reached its conclusion), but that doesn't mean he was capable of mastering
anything.
Who would have lost? Conphas was actively working towards using it for his own ends. So was everyone else. Conphas would have done a superb job had it not been for Kellhus. It took Maithanet, Moenghus, and Kellhus to circumvent Conphas.
So, yes, of course it would not have done what Moenghus intended - that's why he called a Dunyain from Ishual. For Moenghus to succeed, Moenghus needed a Dunyain at the helm (again pointing out, to outwit a human).
What good would have Conphas's deal been, had the Holy War lost first two of its battles, both of which were won thanks, in some part, to Kellhus, and failed to gain any advantage or land? Conphas would've gone back home, assuming he could, with whatever troops he had left, and wait for the Fanim to strike at a much diminished Three Seas and possibly conquer it all.
As for the water Miracle, it wasn't actually a miracle. He found an underground river, and I assume any dunyain could have done that.
Possibly, yes. But Conphas couldn't.
Kellhus was special not for anything he did, but because of what was given to him by others. Did he do unique and powerful things? Yes. I just don't see why literally any other Dunyain (with two functioning eyes) wouldn't have done the same or better.
Because other Dunyain are probably weaker than him, and couldn't have gone as far as he did. Possibly, at least. We don't precisely know, but by the time the first trilogy reached its conclusion, Kellhus had gone leagues ahead of them and had no reason to consider there might be others more suited to his purpose; I doubt there were any to begin with.