Tomra is an optional Underworld town southeast of the Sealed Cave, but it has plenty of nice Weapons and Armor for sale. The Diamond gear is a solid upgrade for Cecil and Kain, and the Tiara is an amazing head piece for Rydia if you don't already have one. (The Wizard Hat is arguably better for Rosa, due to its bonus to Will.) If you don't have a Wisdom-granting rod, or you just like having Rydia attack, the Chain Whip isn't bad. A second Ashura for Edge, a second Ogre Axe for your armored warriors, and a resupply of powerful Mute Arrows round out the options here. You can also buy a Gold Ring for Edge, but Rune Rings are better for your mages.