Battle Skills are powerful abilities that may be used by expending MP. There are are two categories of battle skills: special arts and signeturgy. Signeturgy is sorcerous, while special arts are physical. These skills have range restrictions as well as with normal attacks. Short ranged battle skills will automatically force the user to move within the ideal strike distance before executing.
Hold down either X or O to attack the enemy you are targeting with the skill you mapped to that button. The Battles skill mapped to X will be weaker attack, while the one corresponding to O will be more damaging. Both, however, are still beholden to attack affinities. As strong attacks inflict more damage than weak ones, they also cost more MP to use. As a note, signeturgy that does not deal damage will not increase in potency even if mapped to the strong attack button.
You may map battle skills to either X or O buttons by selecting the Set battle skills section of either the battle menu or main menu. There are a total of four battle skills that any be set together in any combination. They include: short-range weak attacks, short-range strong attacks, long-range weak attacks, and long-range strong attacks.
Signeturgy is a type of battle skill that allows you cast spell that rely on the power of signets. Only certain characters, such as Miki, can use signeturgy. Character who rely on martial arts, like Fidel, cannot. By selecting the Set battle skills section of the battle menu, you can set whether or not characters of whom you are not currently in control can cast signeturgy. You can toggle which signeturgical skills a character will use when controlled by the AI.
As with some special arts, you can cast signeturgy by holding down either X or O. Beware, however, that you may only map spells that target enemies to these buttons. Healing, recovery, and resurrections spells must be cast from the battle menu. Unlike special arts though, you can also open battle menu and select the Signeturgy section to cast signeturgical spells you have learned.
Characters can learn new battle skills by reading Skill Books. Each character can only read certain skill books and thus only learn certain abilities. They cannot learn battle skills through leveling up. Characters become more proficient in a skill by using it during encounters, and once they attain a certain amount of proficiency in that skill, it levels up. Reading skill books for skill that a character has already learned also increase his or her proficiency in it. Each battle skill or signeturgy requires a specific Skill Book. The game will tell you specifically what skill book is needed to learn a new skill or improve an existing one. A Skill Book can also unlock a different skill for different characters. Finally, the higher a skill’s level, the more powerful that skill is. You can get Skill Books as chest loot, quest rewards, or simply make them later on through Item Creation.
Switch out what battle skills each character will employ during combat by selecting Set Battle Skills through either the battle menu or through the main menu under the Skills section. There are four slots in which to set attacked-oriented battle skill: short-range weak attack, short-range strong attack, Long-range weak attack, Long-range strong attack.