I think Jaggers makes an effort to point out (when introducing Molly in a rather strange way) that Molly's wrists show formidable strength. I think this is to be a reflection of her character. It may not matter what her strength lies in, nonetheless, it is a strength.
What I find remarkable is that her daugther we later find is also a woman of great strength. The difference may be what each of them chooses to use their strength for.
It seems that Jaggers made an effort to point out this strength to Pip for a reason. It is as if he was giving him a clue.
I would say that the most remarkable thing about Molly is that she turns out to be Estella's mother. She does not know what has happened to her daughter other than the fact that the daughter was taken and brought up by a rich person. Pip finds this out because he notices many similarities between the two of them.
I suppose it is also remarkable that Molly has been a convict. Pip notices this because Molly's wrists have scars on them as if she has had manacles on her wrists for a long time.
Molly, Mr. Jaggers's housekeeper, is a minor character with a big secret: she is Magwitch's wife and Estella's mother. Molly had been accused of murder, but Jaggers was able to get her acquitted, and Molly became his housekeeper. Her daughter, Estella, rumored to have been also murdered by Molly as an act of revenge, actually is placed by Jaggers in the care of Miss Haversham.
Molly is an interesting character in that so much of the mystery surrounding Pip and Estella lies in her backstory. But more to the point, her "taming" by Jaggers (Wimmick calls her "a wild beast tamed") is an example of the power the lawyer has over the lives of the characters in this story. Molly is a passionate, virile woman who nevertheless is made subservient to Jaggers's calculations. It's an open question how much of Estella's character can be traced to Molly, or to Mr. Jaggers's management.