old Dagger

Hi, everybody, i'm from Belgium and i'm looking for help to indentify this "Dagger" , it was in a box ( WW2 )of our grandfather , i don't even know if its really made in this period .... you can see the small symbols and letters "B" - "W and a star" and an "anchor".
can somebody give me advice? or where can i find more information about it? anyway i thank you for your help, and have a nice day. greetings