The Rods from the weapon shop are pretty much useless for your mages shouldn’t be physically attacking. They do provide three-point boosts to Intelligence and Mind (five with the Wizard Rod), though, so you may want to consider it. The Golem Staff is inferior in that way, so stick with Rods. The Rune Staff boosts only Mind by four.
And magic? You’ll want Thundaga, Blizzaga, Raise , and Curaga for as many people as possible. I wouldn’t really go all-out and go for all four, because you’ve probably begun to get the characters’ Job Levels such that switching jobs may be dangerous. It’s worth the investment though if you choose to have well-rounded characters jobwise (but that’s a lot of grinding).
Curaga is a moderate-power HP restoration, and Raise revives from KO, so they are both important. Protect raises your physical and Magic Defense, though not to the point that buying it is necessary. Erase is Dispel in this game: it removes various positive statuses (i.e. Protect). Raze is basically a try at killing all enemies, but it is grossly inaccurate (think Fissure/Sheer Cold from Pokemon and other OHKO attacks) so not worth buying at all .
Okay, that’s about it. Return to the overworld.