I have a 40-year-old Schrade Old Timer 1540T drop point knife that I have used to field dress, skin, and clean many deer, hogs, turkey, and who knows what else, over the years. The blade is not stainless. I typically wash, dry, re-sharpen, and lightly oil after each use. This weekend, I used it to clean a nasty old duck. I didn't clean the knife until the next day (not unusual) but now the blade is stained black wherever there was duck blood. Is there something I can use to remove the stains other than steel wool and elbow grease?