Looking at different stuff that could happen to this bullet, stuff that's definitely possible within Final Fantasy XI's framework, it seems like literally anything would help in some way.
The Rare tag could be removed, allowing someone who really likes both Corsair and killing Akvan to hold one or more extras far more easily.
The EX tag could be removed, allowing people to just buy and sell the thing. This would make shooting the OompaLoompas' Bullet more like tossing a Morion Tathlum back in the day, which was certainly a punishment but didn't mean "Time to go shoot a giant eye in the...eye...twenty times!"
The Rare and EX tags could both be removed, enabling people to do both of those things.
The drop rate could be increased, which wouldn't change how the system of "Shoot a bullet, go poke Akvan in the giant eye", but would make that system less frustrating.
Akvan could learn how to make enchanted bullet pouches, or start eating people who know how to make enchanted bullet pouches, or develop a very strange digestive system. I'm not really sure how monsters get the items they hold and how we find those items, but anyway, this would help in painfully obvious ways.
Also, these kids just aren't eating my sandwiches...I wonder if I can make s'mores using blocks of rat poison or if the flaming marshmallow will melt them down...