This is a mystery. A shortened Koka Milanovich with professionaly adapted (shortened) scabbard. Maybe this was dan in Serbia, maybe somewhere else. Balkans were the garbage zone for military equipment from Europe.
At least this was a mystery till one nice fellow collector from Serbia explained it to me:
There were 3 versions of Koka-Milanovich bayonets – M1880 without hook, M1884 with hook and shortened version M1880/07 or M1884/07 used mainly by gendarmerie after WWI – and this is my bayonet!