Tor,
I think you are reading it correctly. However, I think the timing makes it almost impossible …. not to mention that "l'ordre national" was not an official name for Légion until after 1870.
Also, it is not overally similar to the actual modele used by the guard chasseurs.
It *is* similar to an hussar sabre of the later revolution/consulate period. And that was the basis for the design for the guard chasseurs.
This is a sabre d'honneur :
You could be awarded an arme d'honneur in the period before the Légion was started : sabre, musket, grenade (it was a brass device for your sleeve), pistols, boarding axe, etc. It was supposed to more or less match the weapon you used when you won the award. The first Légionaires were these guys – automatically.
The armes d'honneur – which were award to company grade officers, NCO's and soldiers – were inscribed with the recitation of the award, as you can see on this grenade d'honneur for an artilleryman ….
Senior officers might get special presentation weapons by act of the government, or from a town or some such – but that was not a institutional practise such as was the presentation of armes d'honneur.