WD-40 and very fine emery cloth can get the surface stuff. The deeper pits are there to stay unless you take a belt sander to it. I give a lot of my blades a WD bath unless the are the old folders with the old type bakelite scales. They tend to fall apart when exposed to harsh chemicals. Most of the good Old Timers have nylon scales that are pretty impervious to solvents.
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"How come my dog don't bark when you come around?" - The Legendary Dr. John
"Learn To Swim, See You Down in Arizona Bay" - TOOL, Ænima, (I hate Kalifornia)