Obtain the Mark of the Lightbringer and return it to Mehlar Dawnblade at the Bulwark in the Western Plaguelands.
I was once a pupil of Uther Lightbringer, founder of the Knights of the Silver Hand. I saw how he mishandled Prince Arthas's training. It led to the destruction of my homeland, Quel'Thalas, and I blame Uther and his incompetence for all of it! And now he has a tomb in his honor - how lovely.
My sources tell me that the scarlet fools are keeping one of his 'holy' relics atop their guard tower near the gates of Hearthglen.
Go to the Western Plaguelands and retrieve it for me.