I know that two Prince skins are the SoT skin and Altair, and Elika skins are Farah and Jade, but the skin selector shows three skins.
What's the third?

Third skin for both are prototype skins.
You can unlock them by completing the game with 1001 lightseeds. You get the last seed at the very end of the game.

Solid snake maybe? There was that altair skin i MGS4...

I added a screenshot of teh third set from my pc version to the article, if anyone is curious.

If I remember correctly, they look like the skins that were in the leaked screenshots way back when the game was still only a rumor.

You only get the Prototype skins by getting 1001 Light Seeds in the PC version.  I got 1001 Light Seeds in the PS3 version and got no special skins.  So I assume they're going to be DLC, or are bugged.  But I'll guess the former.

"You only get the Prototype skins by getting 1001 Light Seeds in the PC version.  I got 1001 Light Seeds in the PS3 version and got no special skins.  So I assume they're going to be DLC, or are bugged.  But I'll guess the former."

Oh, that's interesting and kind of surprising. I guess it's good to be PC user eventhough we got the game a week later.