0000 steel wool and FLITZ works pretty well. If however you have a mirror polished finish, nothing may work short of a professional set up for blade polishing. Best advice is just leave it alone and if you are selling it let the potential buyer know it is there. The value of most knives is not hurt by a small scratch that has obviously not been caused by abuse. In my personal experience, if you look close enough, you can find some kind of little ding etc. on almost every knife, even new in the box and never opened.