Sabre is a weapon which evolved from the cavalry sabre, and so has a few differences from the other two.
Because of its origins on horseback, anything above the waist is counted as valid target area. Also, points may be scored in two different ways. It is possible to score with the point, as with the other two weapons, but most of the time, points are scored using the edge of the sabre, in a cutting motion. As with epée, sabre is usually taught once the basics of foil have been learned.
“Right of way” rules similar to those in foil are used to determine who is awarded the point when both fencers are hit. Because of the speed of sabre, many fight used to begin with both fencers using a "flèche" move - named after the French word for "arrow", this move involves leaping forward very quickly with the arm outstretched, and can cover two or three metres at a time. This made sabre very difficult to referee, and fencers are now not allowed to bring their back foot in front of their front. This makes the flèche impossible, and makes it much easier to determine right of way in sabre.