I have honestly been pretty back and forth on this example of what is generally described as an open hilt (Lguard) saber, which for me had certain notoriety from study on the Battle of Beretschko in Ukraine in 1651 (as I described in my post #7).
As has been noted, the blade appears authentic, but there have been questions on the scabbard and mounts. There seems to have been efforts at restoration which have certain characteristics which can bring doubts, especially in wondering why, where and when would these have been carried out.
With the consternation on the mounts and scabbard, again it does seem the blade, as often the case as the primary and most durable element of the sword, is likely authentic...but questions (for me at least)were toward the markings.
In looking again, the curious oval with arcs at either end marking does seem to have been a known marking, though not as widely known as many others.
In Wallace Collection (Mann, 1962, p.274) it occurs on a German sword of c. 1560-1600, and in configuration bracketed by the familiar 'Genoan' sickle marks (dentated arcs in parallel).
While these 'sickle' marks were apparently widely known in North Italy, the Genoan eponym was leveled primarily as that was the port of export, and these marks used in many locations, As with many markings, there were notable variations and configurations and while perhaps some were favored more by one maker over another, it seems these typically had some sort of application with other meanings.
In looking at the markings on the subject blade discussed here, it does seem the 'germ'
marking as we might call it, must have been placed in situ on the blade in original use, the duplicate mark on the other blade face is worn.
The 'x' markings seem spuriously applied later.
Though the sickle marks were originally Italian, and later widely copied especially in Germany, it seems likely this curious mark was also from Italy in its origins. These Italian markings were also notably copied in Styria at several blsde making centers, and these centers are known to be the most prevalent supplier for blades for Eastern Europe's cutlers (despite Poland having some as well).
Attached page from Wallace Coll.