A "manly man" in the eyes of most women is a strong, self-assured person who can "protect" his partner and make her feel secure without being an ass-kisser. Arrogance, muscles, being a dick, etc. have nothing to do with it.
Oh my god, this. I think these are qualities inherent to being a good PERSON in general, though. A woman can have traits similar to these-- confidence, being self-assured, "strong" (whatever that means), supportive, not afraid of being loving in public-- without having big boobs, nice legs, whatever and
still be incredibly attractive on sheer basis of personality.
As such, I don't view them as inherently feminine or masculine traits, as Theorin said. I view them as qualities of a good person on the whole.