This is the blade created by a special jutsu called Ultimate Forbidden Secret Jutsu: Gods of Creation Fusion used by Unagi Hyuga during his fight with Myoken whihc he used to seal Myoken to the Pole Star. It is the combination of all 3 Blades of Absolute Creation which the three souls: Kyuubi no Yoko, Saitatsu, and Inferno are fused to form the great lord of the middle heavens, a realm even higher then Yhvh.
Minakanushi is known to be the original god of creation that destroyed Myoken's hold of the pre-universal darkness. After his hold was broken, this being broke into 3 beings, then later into 3 blades. This god is said to possess power greater then even Yhvh or Myoken, or even the Blades of Absolute Creation combined.