I vaguely remember reading a series around 1992, which was mostly science fiction and included space travel and possibly opera. it had some elements of hereditary aristocracy which was capable of using special swords (maybe also ships?). These worked by inserting pins into the body of the user and would kill anyone who doesn't have the right genes. I believe there was at least one of the books with a female protagonist. Does anyone remember such a book?
Sounds like the Star of the Guardians series by Margaret Weis. It started with the novel The Lost King, became a trilogy, and now covers seven books.
Elements of hereditary aristocracy - the main action is about a standard Lost Prince in Humble Circumstances re-establishing the monarchy. The aristocracy were also genetically marked by their possession of "Blood Royal" - I don't remember if this was natural or artificial, or if it granted any special abilities or not beyond verifying their identity and allowing access to some technology.
which was capable of using special swords. These worked by inserting pins into the body of the user and would kill anyone who doesn't have the right genes - a major plot element is the existence of
lightsabersswords that required an effort of the mind to activate their blades. They also sampled the blood of their wielder, and would kill anyone who did not carry the "Blood Royal". As I recall, there's a stunning twist at one point where a loyal guardsman chooses to pick up such a sword despite not having the Blood Royal, and is able to use it, though it kills him.
I believe there was at least one of the books with a female protagonist - While the lost prince starts out as the protagonist, the story gradually shifts to focus on one of his female supporters named Maigrey Morianna and her relationship with one of their antagonists.
The original trilogy was released from 1990 - 1992, so that lands square in your timeframe.