This is like 3 months old, and considering we haven't seen anything about it recently, I'd say it was probably just something that particular designer made in his free time.
This was brought up a while ago, and that's actually exactly what it was. This armor is not coming out to Halo at all.
The only reason it was in the Halo 3 to begin with was because of a cross grame promotion between Bungie's game Halo 3, and Team Ninja's game Dead or Alive 4. So unless the two companies do another cross promotion between Halo 5, and a new Ninja Gaiden/ DOA game, then this armor will not be making a return.