Different tools for different places and modes of fighting.
A Claymore, as @amujinx has suggested, is a battlefield weapon: usable in many ways in that context. In single combat, and certainly at close quarters, it probably wouldn’t be as effective as a rapier.
On the other hand, neither of those weapons would be very effective for, say, pirates or sailors to use, which was why the cutlass was developed: you can slash your opponent, and also cut rigging with it, but it’s not meant for stabbing.
A US Civil War-era saber is an effective weapon for a mounted cavalryman: light enough for constant wear, strong and durable for battle use, and both edged and pointed for different types of killing strokes. (You wouldn’t be mounting a charge from horseback and attempting to “stab” an opponent, for example.)
Personally, I’d go with poison, and doctor their water the night before the bout.