Officers have special abilities called War Arts that can be activated by consuming their Art Gauge. With effects such as raising allies' attack power and abilities, the use of War Arts will greatly influence the battle.
War Arts list (partial)
Indomitable: Take no damage from attacks for 15 seconds.
Exuberance: Boosts combo multiplier for 30 seconds.
Encourage: Boosts Allies' Attack for 60 seconds.
Potency: Boosts Attack for 30 seconds.
Fortitude: Allies will not flee for 60 seconds.
Bold: Restores a unit of Musou.
Blessed: Gradually restores Health for 30 seconds.
Agile: Boosts movement speed for 30 seconds.
There is a measure of Favor between the main character and the various Famous Officers. It can go up through events, Tea Parties, and participating in the same battle. As Favor rises, alternate stories may appear, and the Famous Officer's weapon and costume will become available for equipping.
You can fortify a weapon with weapon materials of the same Elemental, which can be found during battle. After fortifying a weapon to max level, you can upgrade it at the Blacksmith. This will not only change its base attack, but also its appearance.
At the Shop you can purchase and trade materials used to fortify weapons, as well as change character parts and equipment.
At the Blacksmith you can Fortify and Upgrade weapons with the materials you get from battle or the Shop.
You can raise Favor with Famous Officers using the Tea Party option at the Tea House. By investing and raising the level of the Tea House, the variety of Tea Parties and the amount of officers that can be invited at once will increase. Also, if the right conditions are met, you can see events unique to the Tea House.
By investing in the various facilities in the Castle Town, you can increase the amount of options available at each one.
With Battle History, completing various objectives throughout the game will unlock panels, eventually revealing an illustration. There are 8 different illustrations in total, offering a ton of replayability to enjoy.
You can compete with players around the country using your scores from Challenge Mode. The rankings will reset after a set period of time, and the chance for players to get rewards for moving up a class or their rank in the previous period will increase with the implementation of the new Class system.

※Images are from the PlayStation®Vita version.