AE has locked the ability to turn in certain rare quests, and that is likely one of them. You won't get banned, but you probably won't be able to turn in it.
Bot 500 combat trophies, then get Steel Afterlife and Basic War Sword from the PVP merge using the merge shop glitch
(https://www.mpgh.net/forum/showthread.php?t=1090861).
You will keep those 100 combat trophies, then merge shop glitch both Behemoth Blades and then get the requirements for the Demanding Items of Nulgath quest to get the DragonBlade of Nulgath.