This is a sword bayonet, in use from about 1885 to about 1905. It was originally designed to fit the Guedes-Castro single-shot rifle, but the rifle order was changed at a later date and the bayonets were shipped with Kropatschek repeating rifles; therefore the tag Kropatschek bayonet in lieu of the original designation.
These were manufactured in Steyr, Austria (this is engraved on the blade back-edge).

They are well made and appears to be a cross between the Austrian 1867 and the English 1856 sword bayonets.
The blade back-edges are marked Steyr and 1885 or 1886 (from what I have observed) in the French style. Single-edged, single-fullered blade; with wood grips.
Scabbards of are sheet-rolled steel, usually blued.