Her brows were thick and filled-in, a strong frame for her face. And, yet, she maintained that smoldering Lily Aldridge-ness that we all wish we were born with. Here are a two things at play here that keep her overall look in the "sexy" category. 1) She kept her hair all tousled and bedhead-y. So her brows might be ready to take on the world, but her hair just came from a makeout session.
And 2) She went for glowy skin. Had she gone matte, she would have looked harsher overall, which can be a fun look, but it's less friendly and approachable.
Keep both these things in mind the next time you want to hit sexy with a bold eyebrow and you should be golden. And guy pretty.