The name/term 'fringia' is associated often with the so-called 'sickle' or 'eyelash' marks that are generally held to have been taken from blades from Italy c.15th c. and the terms 'Genoa' and 'ferara' are also found with these marks.
The fringia marking itself seems more associated with 18th century blades that carry the magical/talismanic symbols of sun, moon and star and are typically seen on German and Hungarian trade blades. The Hungarians sometimes termed a type of cavalry sabre in mid 18th c. 'fringia'. It would seem that Solingen quickly would have adopted this term in marking blades.
While I cannot comment on this sword, I can say it is certainly not Ottoman (even though there have even been suggestions that the fringia term might be Turkish? ). The blade would likely be one of these trade blades, and when we see the hilt, we might have more on where it may have been mounted.
"in the attic" !!!
What else might be lurking in there!!! Nicely done.
ref: "Wallace Collection" Sir James Mann, 1962, pp.255,274,361, also cites discussions on 'sickle marks' and this term from "Zeitschrifte fur Historische Waffenkunde" II, 27,151,270 (sure would love to have access to these German Arms Society journals that go back to end of 19th c.!!