It depends on your strategy. If you play the game properly, you will have all the resources to win. I bought a knife from the shop and enhanced it. Opened all the bags, have all the throwing items, etc.
I would suggest using as few items as possible to make her go to the second stage (Keep in mind you have an enhanced knife equipped). Then just destroy the genital armour, inflect the fear item on her Genital, the key is the drone if you kept it. Once you inflict that fear on her, you can throw a drone and other item on her that deal damage, she will loose hp from that attack + from fear factor as well. Then you can just kill her.
Tbh it depends upon how you deal with this.
I would suggest keeping that broken drone for the giantess. Also, once you use the drone, it won't come back. So make sure before you challenge her, you save your game. Hope this helped a bit.
ALso she won't receive any damage until you remove the armour around the area she is supposed to receive damage at.