Psylocke has change a bit over the years. First with the Kwannon thing, and second after Remender. Right now this is how i would define the character:
Daredevil. Enjoys doing dangerous things. A more extreme form of adventurous which was always her trait in the very beginning with Alan Moore, even under the guise of prim and proper lady.
Confident. I think this changed the most over the years.
Aloof. Especially after Kwannon and Rememder.
Sophisticated
Dissolute. Person or a way of life overindulging in sensual pleasures. I would call her Passionate before, but post-Remender i don't think i can use that term.