One of your arms withers away, leaving behind a stump.
Drawback
You lose one arm of your choice. You cannot effectively wield weapons that require two hands. In addition, you take a –2 penalty on Athletics checks made to climb or swim and on grapple checks.
Special
You may replace your arm with a graft or prosthetic; however, regeneration magic and similar effects will not restore it.
You may take this mutation a number of times equal to the number of arms you possess.