Jolipapa, thank you for the plethora of additional information! :thumbup: :thumbup:
The handle shape of the Agenais definitely resembles that of the typical Spanish navaja, which is considered to be influenced by North African Arabic/Moorish examples itself.
And the chain of cultural influence does not end here!
There is a traditional Hungarian pocketknife pattern, called fejes görbe bicska (literally: a curved pocketknife with a head-bolster):
http://www.bicska.hu/wpress/wp-content/gallery/szakdolgozat-kepek/image047.jpg
The style of the pattern clearly shows some Eastern influence, including the yatagan style blade and the sinuous handle shape.
The earliest known examples are from the early to mid 19th Century.
There is a great deal of speculation regarding the origin of this pattern.
Some say, that it is an indigenous Hungarian pattern, because the handle shape resembles that of the saber handles of the 17th-18th Century Hungarian kuruc freedom fighters.
Others claim that it is a descendant of the Bosnian muslim bicak-style pocketknives. The Austro-Hungarian Empire occupied Ottoman Bosnia in the mid-19th Century, so this is not a completely unreasonable speculation.
The most likely explanation is that the pattern or its predecessor was brought to Hungary from Germany or other Western European countries by journeyman cutlers.
A likely candidate is Jozsef Sziraky, one of the most famous Hungarian cutlers who worked in 19th Century Szeged, a city in Southern Hungary.
Some have speculated that the likely source of the pattern was either directly the Spanish navaja or - through French mediation - the French Laguiole.
But the Boule Yatagan pattern you posted above seems to be even more similar to the Hungarian pattern in question, so I would speculate that it was actually the French
Boule Yatagan pattern which served as the
main and
direct inspiration for the Hungarian fejes görbe bicska pattern:
http://i89.servimg.com/u/f89/12/49/35/11/gimel11.jpg
http://catalogue.gazette-drouot.com/images/perso/phare/LOT/38/2286/6352_couteau8.jpg
Of course the handle shape behind the bolster is different on the Hungarian knife, but that might be the local (Hungarian) flavor - and it too could be derived from other, Sheffield and Solingen type of handle shapes (e.g. the serpentine handle shape familiar from the folding hunter).
If that is true, we have yet another remarkable example the way the great French cutlery tradition inspired the pocketknife traditions of other European countries, from England (Sheffield) to Germany (Solingen) and beyond.