Tnx Black Angel for the rep first when I saw Nero's DT I thought it was Vergil's DT because he had the Yamato shead stuck on his left arm but after that I thought that, if Yamato was Vergil's sword, It's normally that when Nero holds it , it has Vergil's DT Avatar behind of him.And I know why isn't this happening to Dante too.Because Nero has the Devil Bringer that absorbs every Devil Arm that he wields(almost every arm).
But when I finnished DMC4 I looked very carrefully at the last concept art from the gallery and I saw that something covers the Avatar's left eye. And remember that Sparda wears a monocle on his left eye.So I've been thinking Nero has a stronger relation with Sparda than we know.He trully inherited Sparda's power(just like Sanctus states in mission 11).