Ditto what Hawk45 said. If you are really collecting, and you've got an antique knife, don't touch it until you've had it positively identified and appraised. Even then, probably don't touch it. This is true of most real collector, but it is especially true of japanese swords. A lot of people have made the mistake of taking Grandpa's sword he got in Japan during WWII and getting it polished and sharpened by the local knife guy. In most cases, it didn't matter because the sword was a WWII-era factory blade (Showato) which was worthless anyway. But in some cases, Grandpa brought back a 17th century Shinto katana, worth hundreds of thousands of dollars to the right collector. After getting sharpened and polished by the local knife guy in Bumblef***, USA, it was worth $0.