Warzone Commendation

Warzone Commendations are currency items that can be earned by completing warzones. They can be used to purchase specialty PvP items from a commendation vendor.

Source
Warzone Commendations are mission rewards that can be obtained from warzones.

Merchants
Warzone Commendations are primarily used to purchase goods from Jensen and Korus in the Imperial Fleet Zone, and some other dudes to be filled in later in the Republic Fleet Zone.

These Merchants can exchange a character's Warzone Commendations for Mercenary Commendations