Rift Item:Plaque of Achievement  

Earned by completing various end-game PvE content like Expert Dungeons. The Chronicles of Telara instances (introduced with patch 1.5) also reward Plaques.

Players can trade these in for various types of Epic level gear in their faction's capital city.

For the Defiant, the vendors are located in the Catari Command Center in Meridian (6099, 5079). The Catari Command Center is where Asha Catari likes to spend her time. It's also the hub for all PvP related content.

Guardian Vendor accepting plaques is located in the Sanctum of the Vigil in Sanctum (7599, 3099).