Hancock is an exception, or an aberration, if you will. She is love-sick, see?
I would bet you five bucks that Oda won't give women CoC. That's why the whole PoL side of haki was introduced. Some of the more "passionate" characters (meaning, Sanji and most chicks) will get PoL as an alternative to CoC, because for them love is more important than winning fights.