I recently found my Schrade-Walden 172UH knife that I purchased in 1971-72 when I was 16 years old. The knife and sheath are in great shape with no blade nicks or dents. The blade was only sharpened once. The blade is dirty with stains but no rust. My question is should I clean the blade or leave it as is. I don’t plan on using the knife but I would like to display it for my sons and grandkids.