You are weaker than others around you, however you make up for this weakness with your tenacity and ability to adapt.
Lower two of your Ability Scores (Physique, Dexterity, Intellect, Wisdom, or Charisma). This cannot bring the ability score below 1. If ability scores cannot be lowered enough, you cannot take this trait.
Choose one of your Ability Scores (one which wasn't selected to be lowered), and increase it by 1. In addition to this, sub-ability scores for this ability score have a maximum equal to the ability score + 1 (as opposed to just using the normal ability score as the maximum).
This can only be taken during character creation.