I have found this dagger that has been in my Grandads wardrobe for 50+ years. I was just wondering if anyone would be able to tell me about it. If it’s genuine or fake. He fought it WW2 he always said he took it from a German tank wether that’s true or not who knows. There are no markings on the blade or anything. Any help would be greatly appreciated. It’s quite rusty and dirty too. If anyone could advise me on how to clean it without damaging it too. Thank you.