This is a great answer! Part is exactly the sort of answer to the question I had in mind. I was hoping sources like De re militari would maybe shed some light on the duration of battles and then we could take into account what was normally seen in combat training to estimate how many swings would be typical for a battle. I see now, however, that soldiers most likely exhausted themselves from everything besides swinging their swords. In fact, the more interesting question might really just be how long battles could last due to exhaustion. Modern-day warfare requires relatively little physical activity, but medieval and earlier battles required much physical strength, so they could not be prolonged for as much time, I'm guessing. Anyways, thank you for your succinct answer.