If she knows a lot about different countries and cultures, she will stand out from the crowd..And if she's not flashy and looking for attention in the usual, obvious ways, that also make her seem mysterious. Why isn't she following the fashions, why isn't she trying to conform like everyone else?
Mysterious? She has a really complicated and deep personality and intelligence that keeps me digging through her mind for years. She doesn't withhold or withdraw to keep things from me, she's just always showing new pieces of herself because she's just that woman. That would not only make me wonder if I'm ever going o get to the bottom of her, but it would make her and extraordinarily interesting person that would really capture my attention. Sexy? Well there are different kinds of sexy... I can't go into all of them.
Profound intelligence sprayed every now & then without letting me grasp your pattern will keep you mysterious in my eyes.
To me, the words 'mysterious' and 'sexy' do not go together in the same sentence when describing a woman. I have no desire for or attraction to mysterious women. That sounds like drama and head games to me.