By making the XIII saga a trilogy, Square Enix has yet another chance to iterate on the combat mechanics introduced by Final Fantasy XIII. The battle system was improved for XIII-2, and predictably another layer of polish is being added in Lightning Returns. A new trailer outlines the changes.
While it keeps the strategic hooks and real-time combat from previous installments, Lightning Returns puts a much greater emphasis on customizing Lightning with different outfits that grant new abilities. You can see some of them showcased in the trailer, and if that tickles your fancy, the demo is available to try it out for yourself.