Though somewhat unclear, Everbright magic weapon special ability (in Arms and Equipment Guide) may work. Or may not. It makes a weapon "immune to corrosive attacks". But IIRC there is no rule to define what is "corrosive attack" and what is not. So ask your DM.
You can always use wooden/stone weapons and armors. Darkwood shields are already popular. And Ironwood spell (druid) may help. For weapons, you can simply use clubs or staves and cast Spikes (Complete Divine) on it. Or make your favorite weapon via Ironwood spell. There are plentiful of wooden/stone armors in Arms and Equipment Guide, Races of Stone & Races of Wild.
And in all cases, Magic Vestment and Greater Magic Weapon may help you enhancing those "temporally" equipment while you are in the isle.