After appearing back in Prima, you have the option to visit Wisdon or go back to Nabal to collect some extra treasures, which I recommend. Simply head back to the area where you fought SlimeX, and head north until you reach a couple of chests. Open the chests for: a MagicRG, and a Cure. The MagicRG is the perfect Etc. item for Nina, so be sure to equip it. Afterwards, head towards Wisdon, that is, if you obtained the Statue from the man on the Guild's second floor.