This video explains it, one of the hobbits had a wraith-killing dagger that had been forgotten to time and that weakened the Witch King, and the masculine/feminine angle may have had nothing to do with it, beyond it being a funny little irony or example of how prophecy could misdirect or be misinterpreted.
https://www.youtube.com/watch?v=_XCSAuKwLpE
This video explains it, one of the hobbits had a wraith-killing dagger that had been forgotten to time and that weakened the Witch King, and the masculine/feminine angle may have had nothing to do with it, beyond it being a funny little irony or example of how prophecy could misdirect or be misinterpreted.