Ranked Warzone Commendation. It's kind of implicit that it was earned through competitive ranked gameplay because of the name of the commendation.
While no one can say for sure (except Bioware) that upgrading WZ Comms 3:1 was an intended feature, I'm not convinced.
I will concede, however, that it does make some sense allowing the exchange, because otherwise those in Ranked War Zones would no longer play in unrated zones. So there's got to be incentive for those players to play in both unrated and rated. However, Warzone commendations had more than one purpose: buying crafting supplies to name one example.
Now, because of the warzone > ranked warzone commendation exchange rate. This area of the economy is less likely to develop.