(last updated: 12/28/17)
Marathon runners don't run at full speed all throughout the race; if they did, they wouldn't have enough energy left to finish. Likewise, fighters who throw out their best and most powerful attacks in the beginning of the fight probably won't be able to able to keep up the rapid pace. We've implemented a system known as "fatigue" to simulate what happens when a fighter overtaxes himself.
Generally, when a fighter has expended about a third of their Reserve, he or she will be considered Fatigued. When a fighter has expended most of their Reserve, he or she is considered Exhausted. The exact thresholds (cutoff lines) for Fatigue and Exhaustion vary from one fighter to the next, based on their abilities.
Fatigued fighters receive a penalty to attack speed, making it more difficult to hit their opponents. Exhausted fighters receive a penalty to reaction chance, making it more difficult to react to their opponents' attacks. Interrupting is also adversely affected by Fatigue and Exhaustion. The more Reserve a fighter expends, the more severe these Fatigue and Exhaustion penalties become.
Fighters can check their levels of Fatigue and Exhaustion by typing the 'check' command at any point during combat.