Combat Anxiety (3.5e Flaw)
From D&D Wiki
You can't handle the pressure of combat.
Prerequisite: Must not have immunity against fear effects.
Effect: Whenever threatened by 2 or more foes, characters with combat anxiety must make a Will Save roll with a DC of 20. If they fail this check, they will be unable to fight normally. They may still fight defensively if they are cornered, but must otherwise either flee or fully defend themselves. They are not affected by fear by this flaw and can be made frightened normally.
Roleplaying Ideas: The war has scarred you. Aggression doesn't come easily anymore.