hmmm... interesting....
Well upon a close view in sunlight, the material of guard is not different at all and it exibits the same patination than the rest of the sword.
The sword is of very sturdy construction too and there is no sings that someone messed with it.. It looks that it was construced this way a long time ago.
What do you mean by, french duelling sword? I'm unfamiliar with that type, can you post some examples?
Another thing. The blade is not sharpened at all, and it never intended to be. More trapeziodal in section than triangular. Purely thrusting weapon?