The Elites and the whole Covenant in Halo 4 were a rogue group that used scraps for armor and weapons. They weren't communicated with the rest of the Covenant during thr Great Schism, so they didn't know about the betrayal of the Prophets and still believed in the Great Journey. In the Halo 2 remastered and Halo 5 trailer, those were the Elites that still followed the Arbiter (Thel Vadam), so I'm guessing they still had their old regular armor. Depending on which Covenant come out in Halo 5, that's the type of armor that we will see.