Xone, provided that your dark area to be removed is 1/8" wide or larger you are best off free hand carving this with a Rotozip and Sabercut bit. Artists use the Rotozip to do intricate designs in wood. As with any tool there is a learning curve, so dont expect to get it perfect on your first try. Depending on how deep you are cutting and the scale of your carving you might consider looking at the wide range of carving tools available at Woodcraft and other retailers.
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