Thanks Bruce. I get that possibility, but it does indeed look like very local pitting, whereas the rest of the tang does not have it, and the rest of the sword is pristine. It is certainly curious. As Brian indicated, it does have a slightly different patina in this specific area. I am just wondering how it came to be removed. If its a bring back, I would assume the stamp remains as a vet would have no motive to deface it. Nor a dealer to make it appear as an older blade, as the signature is a Showa smith. It is unusual to say the least.