New Summons Menu

Also, keep in mind Espers don't have to teach themselves. Any monster in the game can teach the Esper Summons, so you could also make 'event' battles, without needing to make 'events'; maybe there's a series of mages scattered throughout the land, and talking to one starts a battle, and during that battle they use the summon spell. And bam, you've learned it from them.