Instructions
Go to the Bloody Foothills. This is just outside of Harrogath, which is marked on your in-game map.
Speak to Larzuk the Blacksmith, who asks you to kill the evil Shenk before he will offer any service.
Go deeper into the Bloody Foothills. Defeat all of the minions you come across. At the end of the path, you find Shenk.
Defeat Shenk. He is not a boss, but is merely stronger and more durable than the minions, so defeating him will take a little longer.
Return to Larzuk, who offers to socket your armor. Select your ethereal armor to complete the quest and upgrade the armor.