How many guys just say , "EYES", because they are too afraid to say T and A for fear of being labeled as insensitive boors?
I mean, that pic that Sprint posted does not highlight any eyes, but it could help get me through a stint in jail, yes, you were all right all along, I am.

I think people that say eyes do so because it is easier than trying to define just what it is that makes a woman sexy, because as someone who went out with an identical twin for a long time, I learned first hand that looks are very much in the eye of the beholder, and how one twin can be so very attractive, whilst the other repulsed me, made me examine what it was about, because looks obviously did not determine my feelings.
We all know that any woman can be sexy, and I think it is a lot to do with facial expressions, and body language, all determined by her state of mind, and attitude, and this is what the "eyes" men probably feel too, and use the eyes as shorthand for saying that.
I remember the book and movie, "The Unbearable Lightness Of Being", which was a lot about male/female desires and relationships, and how subtly a person's perspective can change things.
The movie celebrated sex and love and life in a very open and honest way, with the most natural sex scenes I have ever seen on film, with lots of laughing and plain exuberant fun, as well as times of deep intimacy and real sharing, it remains a favourite movie of mine to this day, and it truly celebrated women.
This was one of the very rare exceptions where the movie is far superior to the original book, written by Milas Kundera, which held the unfortunate misogynistic attitudes we see from many men, and whilst it claims to celebrate women, it actually comes across as celebrating a far shallower ideal, being that of a womaniser collecting scalps, which demeans, rather than extols the value of women, even in casual sexual encounters.
Now this tangent does have a link to the original question of what makes a woman sexy, and one scene in particular, shows a good example of a woman going from plain, shy, and dowdy, to confident and sexy, when the artist, Sabina (Lena Olin) starts to photograph Tereza (Juliette Binoche) and encourages her to be sexy.
Sexy is, a nice smiling face offering the promise of fun and laughter, eyes that go from glinting smile, to steamy and smouldering, a confident bearing and a hint of an invitation of intimacy, and an openness that inspires confidence in others.
Women who may not be supermodels can still be super sexy, and even someone's ideal physical fantasy would be nothing, without those qualities of sexiness that anybody can have.