Grokom Deatheye at Shadowmoon Village wants you to bring him Mazakradon's Glaive and Morgroron's Glaive.
With a larger supply of this material, I can forge a weapon suitable for you.
The two pit lords at Legion Hold, Makazradon and Morgroron, have already been equipped with these anti-demon weapons. Capturing those two weapons should provide us with enough material to make your weapon, and then some.
I can't wait to bring the battle to the enemy using these weapons. That'll teach the Legion to trifle with anti-demon magics.