Tribal Armor
They intentionally forgot about it.
Since the first beta week-end this armor could only be found in PvP and was labeled “Masquerade Armor”, which is the name of another PvE set (and this set couldn’t be found in PvE).
Ever since players kept asking what was the deal with it because heavy and medium didn’t have such a problem (medium has another one). Not a single answer.
When the wardrobe was announced, players figured out that there will be a new way to get those armor. Like in a reward track. Alas nothing and Anet still hasn’t said anything.
So all you can do is hope.