I'm going to take a stab in the dark and assume you are doing nothing today.
If that's the case, go to an electronics supply store (such as Vetco or Radio Shack) and buy some Ferric Chloride etchant. I dilute mine to 20% (1 part FC to 4 parts water). Put it in a glass or plastic container, NOT metal. Mix up just enough for your etch. I use an emptied and cleaned olive jar for most of my etching.
Before dipping your blade, clean it THOROUGHLY. Wear vinyl or Nitrile golves, to avoid getting body oils on the piece you are cleaing. Clean it with Windex first. Rinse with clean water. Wipe it down with acetone. Rinse in clean water. Dry it off. Drop it into the etchant and leave it sitting until you have the desired darkness and depth of etch. I usually leave it in for 30 - 50 minutes. Avoid the temptation to remove it and check it frequently, as this will create an uneven etch.
When you remove it from the etchant for the last time, quickly rinse it with clean water. Wipe it down with clean cloth or paper towel. Wipe it well, a lot of black stuff will come off. Use a solution of baking soda and water to totally stop the etch. Rinse it again in clean water and wipe it down.
After that how you finish it is up to you. I usually give it a light sanding with 2000 grit sandpaper.
