The rapier has a swing cooldown of roughly 1/4 a second. It takes five hits to knock an opponent down. Due to its difficulty at hitting opponents knocked down, you will have to then stomp twice to kill.
The rapier's next to non-existent swing cooldown means players can spam swings constantly. Good movement is important to dodge enemy swings but also be close enough to counterattack. Wait for an enemy to miss a swing then pursue and attack to maximize your chances of winning.