Sentinel's Medallion

The Sentinel's Medallion is PvP reward necklace for the Alliance from the Silverwing Sentinels. It can be purchased for the correct amount of honor points depending on the level. There are 5 versions of this necklace which correspond to the 5 level brackets in Warsong Gulch.

The Horde equivalent is Scout's Medallion.

Source
The Sentinel's Medallion is sold by Illiyana Moonblaze in Ashenvale. Previously, players had to have Honored status and the correct number of Warsong Gulch Marks of Honor in order to purchase this necklace. Now it can be purchased with honor points alone.