Clare was also noted to have an odd body. So it's a general Claymore thing, just not really described. Also, Teresa and Clare are offensive types, so regeneration is limited.. When Clare was inspected after getting hit through the gut in the start of the story, Rubel states that if she gets hit there again due to the injury's severity, she could die. So they probably can't close up major wounds perfectly, resulting it deformities/scarring.
>"What if that kid... saw that body of yours? What would he think?"