What physical defects in a slave prevent their validity for expiation by freeing?

Primary text

A slave who is blind in one eye, has a limb severed (hand or leg), is paralyzed (shalal), is missing the thumb, index finger, or middle finger of a hand is invalid for expiation. This is because the utility of the hand is lost by the removal of these fingers. Removing the ring finger and pinky finger from one hand is also invalid because most of the utility of both hands is lost thereby. However, if a hand and a leg are each completely severed, it is valid because the utility of the palms remains. Cutting one phalanx (anmulah) of the thumb invalidates it, as its utility is lost, given it has two phalanges. If the cut is from other fingers, it does not prevent validity, as they become like short fingers; even if one phalanx is cut from every finger except the thumb, it is still valid. If two phalanges are cut from a finger, it is like cutting the entire finger, as its utility is gone. This entire delineation is the position of Shafi'i.