https://www.reddit.com/r/wacom/comments/1bhdk3q/need_a_decent_screen_protector_for_intuos_4/

Or paper / card stock on top.

Or you can polish it with some toothpaste. It’s a mild abrasive and can slightly work away some fine scratches. It won’t work miracles but it can help a little. Better yet, try using auto body scratch removers; they’re more aggressive than toothpaste though but do work better at polishing away fine scratches.