I’ve been playing Phantasy Star IV since 2009, when I was 8, but this is something has absolutely never crossed my mind.
What if you went into battle without items? This has to be done before you get the Control Key, as from then on, there are items that you can’t discard.
If you discard all your items, what would should up in battle?
People have probably already tried this, but the red backpack icon is gone. Amazing that it never occurred to me to test that.