You give Ivory Crafter Dark Revenant Thighbone.
Ivory Crafter tells you, "Aha! A Dark Revenant thighbone, quite exceptional!"
You've earned 7,500 experience.
Ivory Crafter gives you Trade Note.
Ivory Crafter tells you, "A fine reward for your formidable deed"

Note is a "D" note
Also thanks to Hentaya Goldenelm @ HG for the update.