@XL is it a thing? I forget if this world established them or not. If so I suppose it is goofy they wouldn't have them- though actually, I see the logic given a sword probably can't consume potions, and fran's mana is pretty limited either way.
For that matter, with the HP to MP thing... does the sword even have HP in terms like that? And then Fran obviously doesn't have a ton of either HP or MP herself if anything.
I'll definitely admit some of these MIGHT be feasible, but honestly that doesn't at all make the lack of them weird.
A better critique is why they'd go to the island knowing they might run out and have issues, not why they don't have specific backups that wouldn't necessarily work at all. But hey, read whatever you like anyways, it's no favorite of mine though it's not as bad as you're acting like either.