Couteau, from Old French coutel, from Latin cultellus a little knife.
Couteau really means "knife" in French, not sword or saber. Sword could be "épée", saber would be "sabre". Although it's always hard to know what the old use for these words used to be.
I couldn't find an equivalent to the English term "hanger". The wikipedia page links to the French "sabre d'abordage" page, which would be a boarding sword.
The collector who identified this sword as a "19th century german hunting sword" called it "dague" (dagger) and "couteau" -de chasse in the same email ...
I didn't have time to take a picture of the blade today, but I can assure you again there are sadly no other markings.
Thanks to all for your interest !