I have to agree with reinhard on certain points. While I have more confidence that this blade really is old, there are things on it that make it look "strange".
The nakago looks a little weird to me. It seems a little "unfinished".
To me, every time I see a hi that looks like that, I think "showato". The nakago rust tells me otherwise. I believe the nakago may have been hastily finished if suriage.
The hamon just doesn't look right to me either.
Perhaps it was modified for War? May I ask how you obtained the balde?
With these things in mind, however, I still believe it is just an old (Pre-Showa) blade in need of some TLC and good polishing.
Boy, I am editing this a lot! :D This is quite embarrassing!