I have been busy this week so its a bit late...
Don't rage over this one-
Low- Slay the Diamyo Hemitaur using the Longsword in the Battle Training quests, Without any Items, under 5 minutes.
Med- Slay the Shen Gaoren using the Anvil Hammer.
HARDCORE- Slay the Slay the Khezu On the first lot of Nekohts quests using the Ceanataur Blade Stinger