I wanted to keep the Golden Piercing knowing that it is a one-time item so that I have a full-inventory profile (I play Zelda), but I guess I should be quite fortunate that I was able to keep everything else after the annoyance from how cheesy the boss can be.
Not helping the fact that, besides Esix being unlikeable with how the story was conveyed (in my opinion), this is the ONLY instance a JRPG battle occurs, and is all in its unhinged glory.