The Hero We Need, version 6.21 introduces a new boost for your combat battles. Learnable skills! This update lets you acquire new skills in battle after you unlock the Aether Realm for your main party in the Nightgale section. They're simply bought with experience points, directly from the skill menu!
Each member has their own (and more to be added) that you can purchase to enhance your fighting experience. Hopefully this makes the battles more dynamic with the options you can choose to stack your deck against your enemies!