Trivia: Carlos Gallardo, who played El Mariachi in the prequel to Desperado, El Mariachi (1992), was given a minor role in Desperado as Campa, the mariachi with the two machine-gun guitar cases.
Trivia: The same Ford pickup truck that was used (over and over again) in El Mariachi can be seen when he crosses a street near the beginning, you don't need to look very hard to find it.
Trivia: The American girl who is criticising the service in the Tarasco Bar (just before Quentin Tarantino walks in) is actually Robert Rodriguez's sister.
Trivia: The gun shaped like a penis from From Dusk Till Dawn is in Antonio Banderas' guitar case in this movie.
Trivia: Made for just $7m, but that was a thousand times more than the budget for El Mariachi.
Trivia: Despite playing a fairly prominent character, Danny Trejo does not have a single line of dialogue throughout the entire movie.
Answer: Having a tough-looking, silent henchman/henchwoman is a pretty common trope in action movies. She's basically there to look tough and mysterious. I wouldn't read into it more than that, especially given how minor the character is. (Minor enough that I had to Google her, because I couldn't even remember her, and I've easily seen this movie a dozen times over the years).
TedStixon