"The Sex" in Frankenstein

For a literary topic, I had to research women in Victorian society in relation to Mary Shelley's Frankenstein. Though I realized that there are underlying tones of feminism in the text, I did not realize the extent of the tones until doing this deep reading.
The base of the feminist tones found in the text lie mostly in what the author knew of her mother. Mary Wollstonecraft, mother to Mary Shelley and her stepsister, Fanny, was a political activist who advocated for the rights of women in Victorian society. She is best known for her feminist writings, the most famous being Vindication for the Rights of Women. The writings of Mary Wollstonecraft greatly influenced Shelley's writings.
One common feminist argument against Frankenstein is what the creation of the monster represents. In Victorian Britain, women were seen as only having one use: the ability to procreate. A woman who did not become a mother was considered abnormal, and a woman with the inability to have children was pitied. In the novel, the creation of the monster is supposedly a representation of the inability of men to give birth to a human life form and therefore a demonstration of the power women possess over men.
However the theme can be carried even further than this. During a lively discussion of the works of Mary Shelley, a friend of mine briefly mentioned an article she had read which analyzed the importance of Safie in Frankenstein. I had never considered her an important character before; she was in the novel for a very brief period and it seemed as if she had been of little benefit to the monster besides the indirect role she played in helping him learn English.
However, she plays a more significant part than I realized. She is literally the center of the novel; her only mention is in the middle of the second part of a three part series. Additionally, she authored letters relating her tale to her lover, Felix. Though the content of the letters themselves is of little significance, their presence is one of the most important parts of the story. As the monster said, "they will prove the truth of may tale." Of all the stories told, whether it is the story that the monster relays to Frankenstein or the story that Frankenstein relays Robert Walton, the letters that Safie wrote the Felix are the only proof of any journey taken in the story. The letters prove that the monster once found himself under the "protection" of a blind man and his children. They prove that Frankenstein created a human like life form. They are proof that Robert Walton even came into contact with Dr. Victor Frankenstein at all. In the midst of all of these stories, this is the one shred of evidence that supports them, entwines them, and proves them all to be the truth. And the person who supplied the proof to such an unbelievable story, the person who contributed the only existing piece of evidence, is a person who society is the least likely to believe : a woman.
Additionally, a major aspect of the novel is who receives this proof. There is only one character who possesses knowledge of Safie's letters, hears the monster's stories, hears Frankenstein's stories, and hears Robert Walton's story. This character, who doesn't even appear in the book, is the single character who is able to act as a god figure, an omnipotent power who is the final hearer of all confessions. The character that possesses the most knowledge of the entire tale is Robert Walton's sister, Margaret Saville. Mrs. Saville has no speaking part and contributes no information, yet she is the only person who knows every story: yet another occasion in Frankenstein where the only proof of the story is in the hands of a woman.
Though I have not fully assessed the significance of the all-knowing character being a woman, I am aware of two things: her omnipotence, paired with Safie's letters, show women as the possessors of a vast degree of knowledge on which the proof of endeavors rely, and the initials of Margaret Saville are, eerily enough, the same as those of Mary Shelley.