This is a Swiss knife bayonet manufactured from the period of 1918 through WWII. As with other Swiss bayonets, they are exceptionally well made.
Double-edged high-quality steel blade with raised medial rib, wooden grips.
Bayonet was made for the Schmidt-Rubin Rifles and K31 Carbine.
Overall length is ~17"; blade length is ~11-3/4"; hilt is ~5" in length; nickel-plated steel furniture; serial number is found on the cross-guard.
Most common manufacturer's marks were "WAFFENFABRIK NEUHAUSEN" (Neuhausen is a city located in Switzerland near the German border), also ELSENER SCHWYZ (AKA Victorinox).
Scabbard is all-metal "blued" scabbard, with leather frog "tongue;" rolled-sheet-steel with ball-finial.
Switzerland declared itself neutral in both world wars, and had zero military involvement;
reportedly, they did not supply the German military with any weapons, equipment, or accoutrements.