Women are incredibly vulnerable in Sherlock Holmes's world, from poor Helen Stoner's murdered sister in "The Speckled Band" to Miss Rucastle, locked up by her own family in "The Copper Beeches." There are contrary examples of women who manage to determine their own fates – Irene Adler and Hatty Doran, of "The Noble Bachelor," for instance – but their independence is so unusual in the context of Holmes's world that it has to be explained in detail to make it believable. Adler can move around in society widely because she's an actress and an adventuress. And Doran can take care of herself a bit more because she was raised in a mining camp until she was twenty.
"Properly-bred" femininity appears to be in constant danger of cruelty and damage. The flip side of this vulnerability, though, is that these women are often portrayed as morally superior beings: devoted, faithful, self-sacrificing, and above all, domestic. This theme shows the influence of the prevailing "Angel in the House" model of womanhood in the Victorian era.
Irene Adler has greater social mobility than other women characters in Holmes's adventures because she's an actress and performer and so, like Holmes, operates outside of mainstream society.
Holmes and Watson strongly identify women with emotion and men with reason.