If you still want to have her keep a bit of femininity, I suggest adding a half skirt over whatever pants you choose. Adding a pinstriped half-skirt over leather (or faux leather) pants might look very badass. Adding lace in playful places would also help to suggest a softer side. But, as VerrinEleni said, make sure you keep it looking functional. It wouldn't make sense for her to wear heels that are too tall or skinny, so a chunky boot would look great.
A corset might be too restricting. However, you can always go with a waist-cincher. Wittles your waist, yet still allows you to breathe. A vest could work too, just make sure it's appropriately punk / steam. You wouldn't want it to look too new, so distressing it or adding unique details is a definite.
As for the winter part, I would definitely suggest at least one of those cute cropped jackets. They'll keep your arms warm, but if you have a cute top on, you would still be able to see it. Then you could have a nautical- or old-themed scarf on as well. Gloves are essential, even if they're just fingerless.
I hope I helped somehow. xD Have you thought of any props?