The KS98 (Kurzes Seitengewehr) is a "sawback" knife bayonet manufactured from the period of 1902 thorough WWI. I have no doubt they were also used in WWII. They were manufactured originally for Machine-Gun Units but were also used by various other units.
There are a number of variations, mostly with grips and attachment method. Most of these will be found with Imperial German markings.
Well-made, single-edged steel blade with sawback, wood grips. This is not a cut-down variant of any '98 series bayonets.
All-metal "blued" sheet-rolled-steel scabbard.