Hi Michael,
Why do you think the motto
Honneur et Patrie replaced the Eagle and Imperial Garde engravings?
Perhaps the motto is a remnant (not a replacement) from the origin engraving, as it was the motto of the
Legion d'Honneur, established by Napoleon as the French highest condecoration.
Your sword would indeed be a
Sabre d'Honneur, with which Napoleon presented 145 officers of
La Garde.
There would be three different models, to distinguish the rank of the officer presented.
Apparently this insignia was altered in 1814, with the removal of the eagle and, in the case of condecorations, the face of Napolen was replaced by that of Bourbon King Henry IV, whom could also be the guy on the cross hilt of your sword.
Hope this helps ... and expect it is reliable