If you did not see a grain pattern in the steel when you polished it like the pics above then it's a modern steel gunto blade and not Nihonto (traditional forged). Sometimes Nihonto blades were given military fittings. Gunto cannot be sent to Japan and most polishers will not work on them. There is a separate category of collectors, study and suppliers for work and parts.
It helps to know which you have.
It helps to know which you have.