The victory at Caraskand seems unlikely. Unlikely...but not impossible. Battles have been won in similar situation in real life. What is said here:
Hmmm but the human spirit conquers all!
Is true, to an extent. In battle, an iron age set piece battle especially,
will to fight is arguably the most important thing there is. Like Caesar's final battle with Pompey, when by all rights he should have lost, he prevailed. It was all down to a bit of luck AND the fact that Caesar's men must win or die. Pompey's men had other options. The same is true a Caraskand. Every man of the Holy war knew that he must triumph on the field or die that very day. The Fanim on the other hand, had the option of fleeing if things started to go bad. Sun Tzu has a quote about it that I can't entirely remember that goes something along the lines of "If you want to learn how hard men can fight, leave them no avenue of retreat."
Also never underestimate the power of
shock. The human mind can take tremendous abuse
if it is prepared for it. Surprises though? Surprises sap your morale with alarming alacrity. A soldier that's been in a dozen battles can develop PTSD from a single ambush.
The Fanim expected an easy victory against a starved and despairing rabble. When they fought screaming fanatics with iron wills instead, they were left shocked and disoriented. Much easier to rout.
These two things combined, the desperation and superior morale of the Men of the Tusk, and the lesser will to fight and surprise employed against the Fanim, led to the Padirajah's host being routed.
noooooooooooooo
Why does this dismay you so? Kellhus is a
monster. He deserves to be broken. The only reason he's even a protagonist is because the antagonists are
even more monstrous.