I found a Imperial fixed blade tucked away in an old tackle box that I haven't used in several years. I found the knife while fishing and just stuck it in the box. This was before I contracted the knife collecting fever, of which there is no cure only treatment. The sheath is dirty and needs a good cleaning. What do you suggest for cleaning the sheath and what do you use for periodic treatment of leather. All my fixed blades are less than 2 years old and I'm thinking they should probably…