The joke isn’t important. What is important is that imo it makes 3PO’s sacrifice and an entire portion of the film pointless because Rey didn’t simply hold the dagger while feeling either angry, fearful, passionate, aggressive, etc.
She seems to demonstrate those emotions quite frequently. So it would be like going through a whole bunch of effort and sacrifice to figure out how to solve a problem only to be told that the answer was right in front of your face the whole time. Sure, you could argue it’s tragic, but I see it as worse writing than what we currently have.