Related to the German flammenschwert (flame sword), the flamberge (flame blade) was a rapier variation named for its undulating blade. Found among the upper class in the 17th Century, the flamberge variant is also seen in the transitional rapier, the ancestor of the smallsword.
Flamberges are indeed showy, but it was claimed the waves of the flamberge would inflict more damage in one’s opponent. That claim is somewhat questionable. Regardless, there is little doubt that the undulations in the blade would impart significant vibrations upon contact with an opponent’s blade. This must have been a jarring experience when executing an attaque au fer, or even a simple parry. I suspect that sentiment du fer would be seriously impacted for both parties.