if you're a rusher the 3 points in fatigue is 100% worth it. and it's global fatigue reduction, the notation is in error (at least it was in version 1.0 of the game that may have changed now).

as far as combat, you definitely don't want to go into a fight being fatigued. related, 2nd wind is way underrated. whenever we rush we take great guard and when we start on player 2 we pop the 2nd winds.