Oh, ok! I didn't knew that, i supposed that you could get the difficulty decrease just by talking to Eruke. Guess i'll have to respec some characters to beat that 22 Intimidate check. Annoying, but doable. Thanks!
Edit 06/11: I can confirm that, as a Seeker chosen, passing all the skill checks (Religion, Metaphysics, Diplomacy and Intimidate) you can resolve everything peacefully. I can't remember what i told Whehami after the 22 intimidate check, it was something on the line of reminding him what his duty his and he's not a proper slayer if he can't slay boredom. I don't know if EVERY skill check is necessary, since i've not tried selectively.