The Imiriaran Cycle (Old)
1) Make a background option, Blind. Blind has the following abilities:a. Makes you blind. b. Gives you a +3 Bonus to perception, as long as sight isn’t involved. c. Grants a +2 bonus to hit creatures with total concealment. Those add up to her being three behind everyone else to hit.
2) Additionally, give that character a +2 bonus to their prime stat. This takes their to hit to being two behind but gives a +1 to damage.
3) Since they also give up combat advantage, throw in an extra feat as a kicker.