List of Final Fantasy X auto - abilities Unlike command abilities , auto - abilities in " Final Fantasy X " automatically take effect and can be assigned to weapons and armor , similar to support abilities in previous games . All pieces of equipment can have a maximum of one to four auto - abilities . Most equipment have auto - abilities already assigned to them when acquired , but once the player reaches Guadosalam , they can customize auto - abilities onto equipment as long as they have the required number of items , and as long as the equipment has at least one empty slot . Once an ability is added to a piece of equipment , it cannot be removed . Brotherhood , Celestial Weapon s , and non - empty - slotted equipment cannot be customized . On occasion , customizing equipment may change the name and appearance of that equipment . For example , adding the Firestrike ability to the Variable Steel will change its name to Flametongue . Below is the list of auto - abilities that can be customized to weapons and armor . Aeon auto - abilities . Aeons also have " equipment " , though it is not generally visible in - game . Their weapons initially contain an empty slot , followed by Piercing , followed by - , and finally another empty slot . Bahamut , Anima and the Magus Sisters have Break Damage Limit instead of the first empty slot , and Valefor does not have Piercing . Once the respective Celestial Weapons are upgraded with at least the crests , the first empty slot changes to Break Damage Limit . Their armors do not change ; they always contain Sensor , a blank slot , Break HP Limit and Break MP Limit ; the elemental aeons have their respective element Eater instead of the blank slot . Dummied auto - ability . One other oddity is that an ability exists in the code ( though it is unobtainable without a cheat device or save editor ) called Curse Ward . Mechanics . Some equipment abilities do not work exactly the way that would be expected . Any ability that increases a stat by a percentage , in the event of multiples of these equipped at once , the percentages are added together before applying the effect . For example , equipping HP + 30 % and HP + 20 % would result in a 50 % boost to HP , not a 56 % boost as may be expected . Additionally , apart from HP and MP , these abilities do not affect the stat itself , but rather , they affect damage . For example , Strength + 20 % does not increase a unit ' s Strength stat by 20 % , but rather boosts any physical damage dealt by 20 % . This difference is important for two reasons ; because a 20 % increase to the stat does not necessarily correspond to a 20 % increase in damage as the formula is not linear , and secondly because " attacks which are determined by Strength " and " attacks which deal physical damage " ( and likewise for Magic , and for defensive stats ) , while often going hand in hand , are two different things . For example , Fenrir ' s attack Fangs of Chaos is considered physical , but is not affected by Strength or Defense ; in this case , Defense + 20 % would still reduce the damage . Overdrives are considered special damage rather than physical or magical , and as such , Strength + 20 % has no impact on their damage . Status abilities work in a similar way . Status - touch abilities increase the chance of infliction by 50 % , while Status - strike abilities increase it by 100 % . If both are together , which can be achieved by customizing the - touch first and then the - strike , the weapon will have a 150 % chance of inflicting the status . This can make a difference against enemies with partial resistance to the status . This further combines with the chance that an attack carries ; for example , if one has Darktouch and Darkstrike equipped and uses Dark Attack , the result is a 250 % chance of inflicting Darkness . Status resist abilities provide a 50 % resistance , which is subtracted ( not multiplied ) from the chance . For example , an attack with a 80 % chance of inflicting Silence , used on a character with Silence Resist , would have a 30 % chance of working ( not 40 % ) . Status proof abilities do not give a 100 % resistance , but rather " perfect " resistance — no matter how high the infliction chance is , status proofs ( and Ribbon ) will always protect the unit , unless the attack is one of the few that bypass protection . For the most part , immunity - bypassing statuses cannot be prevented , but there is one exception : protection - bypassing Slow will still be prevented by Auto - Haste ( or active SOS Haste ) . There are attacks that always inflict a status unless the target is perfectly immune . Aside from some enemy attacks , the status Buster skills , and all status - inflicting items , except Farplane Wind , carry this property . Abilities that modify AP or gil gain only work if the user is on the frontline at the end of the battle .