If you've been playing World of Warcraft for any length of time, you've probably come across Spirit Shards. These little items are used for a variety of things in the game, including creature taming and resurrecting other players.
If you're looking to complete the Alterac Valley Mark of Honor achievement in World of Warcraft: The Burning Crusade, then you'll need to head to the Alterac Valley quest hub in the frigid north of the Hillsbrad Foothills.
There are a few options for turning in your Mark of Sargeras in TBC. You can either go to Shattrath City and turn it in to A'dal, or you can go to Silithus and turn it in to Calydus.