Should I do restoration on this dagger?

My boyfriend came across of a knife in his back yard when he was about nine that had a swastika on it. Yeah, I know, who the heck finds one just chilling in their back yard? Anyways twenty years later, last week, his mom returned it to his possession, now that he is finally old enough. I looked it up by the appearance and the engraving on the blade and it is a WWII Hitler Youth Dagger. I could barely read the engraving because there is A LOT of rust on it. He has no interest in keeping it and we were just wondering if we should or could have the blade restored to sell. He knows someone that can sand blast it for free of charge but we weren't sure if it would affect the etching. We don't want to do anything that will take away from the value. What would you recommend?