DMG 3.5 p27, "Variant: Damage to Specific Areas" gives effects if a specific limb is damaged but not destroyed. You can probably extrapolate from those rules if you need to.
Or if you are just itching to buy a new book, I suggest Torn Asunder: Critical Hits from Bastion Press. It has variant rules for Critical Hits, Healing and Artifical Limbs. It also has new spells for grafting a limb back on. I ordered mine from Talon Comics.
I have a 16th level fighter who is missing the pinky and ring fingers on his off hand. What penalty do you think he should get when he fights with two weapons?
He is unable to get the fingers regenerated by normal means because of an old artifact curse he picked up earlier in his life.
How about a penalty to the attack unless he is willing to risk dropping the weapon? Say -2 attack/damage penalty since you need to pull the swing a little to keep from losing your grip. You can still take the full swing but risk a DC(10or15) dex check to lose your grip. This kind of penalty may go away as the player adapts his fighting style. However it should always apply in disarm checks.