Human Shadow knight of Innoruuk (aradune) did this real easy fast at 60. Go to kurns tower and kill every skeleton upstairs and in the basement until you see glowing skull. I believe only the "scalebones" can drop the skull. Took me about 10 min of killing. Could not figure out the quest giver's keyword. seems to have been changed or broken. "I accept the calling" advanced the quest, though i guess you could skip the optional talk and just hand him the skull and kukri.
Log:
[Sat Oct 17 18:18:05 2020] You say, 'Hail, Lord Korzin'
[Sat Oct 17 18:18:06 2020] Lord Korzin says, 'What is it you seek? Eternal suffering?'
[Sat Oct 17 18:18:14 2020] You say, 'I seek eternal suffering'
[Sat Oct 17 18:18:14 2020] Lord Korzin says, 'Then follow the words of Cazic-Thule and may his blessed curses rain upon your soul as they shall on all of his faithful servants.'
[Sat Oct 17 18:18:26 2020] You say, 'i accept the calling'
[Sat Oct 17 18:18:26 2020] Lord Korzin says, 'As if you had a choice. Seek out the tower of Kurn and find the Skull of Torture. You should be able to easily recognize this skull as it glows with the power of Cazic-Thule. Return it to me with your squire's khukri and I shall reward you with the knight's khukri. Go at once.'
Turn in:
[Sat Oct 17 20:31:13 2020] Lord Korzin says, 'You will be rewarded with the knight's khukri when I have possesion of your squire's khukri and the Skull of Torture.'
[Sat Oct 17 20:31:13 2020] Lord Korzin says, 'Excellent work! You are no squire. You are now a knight of the crusaders. Your next step shall be zealot. And every zealot wields a magical khukri.'
[Sat Oct 17 20:31:13 2020] Your faction standing with Crusaders of Greenmist could not possibly get any better.
[Sat Oct 17 20:31:13 2020] Your faction standing with Legion of Cabilis could not possibly get any better.
[Sat Oct 17 20:31:13 2020] You receive 1 gold from Lord Korzin.
[Sat Oct 17 20:31:13 2020] You receive 1 platinum from Lord Korzin.