The scars are almost exactly the same style as the stars that indicate a Goku uniform's rank. Remember what the stars actually mean? It's the percentage of the thread that's made of life fibers: a 1-star has 10%, 2-star has 20%, and a 3-star has 30%. The presence of the star scars on Ragyo is likely foreshadowing that she's a life fiber being. I only count 7 in the full shot, so either that specifically means that she's only 70% life fiber (having been corrupted by them when she was older rather than as a child like Ryuko or Satsuki), or the specific number is unimportant and the idea is that she herself contains life fibers, and at a higher percentage than any Goku uniform.