INK STAIN ON OIL FINISH: Any solvent used will likely cause the ink to bleed into the wood grain making it even worse. 1) Contact manufacturer of pen, possibly thru 800 number and ask advice. 2) Get an ink eraser from an office supply store and try erasing. 3) Carefully & slowly try household bleach. Use a Q-tip. Start by testing one small spot. If the blue starts to turn green then yellow, it's working. Color and gloss level would probably have to be rebuilt afterwards. 4) Last resort is careful sanding, realizing veneer is probably thin. Finish work would again be required. If finish is a surface finish like lacquer, then solvent cleaners like lighter fluid and naphtha could probably be tried with more success.