@Asuma exactly , so now the example of the enemy can finally be useful : if you never played the game before you may believe that it isn't possible at all , but the example of the enemies show you that it actually is , basically , to normally use a mystic arte you need to unlock the skill the i don't remember the name about ( but fortunately there is plenty of guides on internet where this is explained since 2009
) , once you have that skill , in combat you need to press the command for the regulard arte , and just like in a combo , press immediately the circle button ( if i remember correctly ) , so without this method in combat , there isn't any trigger for the mystic arte , but when you fight for example against the final boss , you can even take a look at youtube for that , you will see how enemies with mystic artes can use them without the procedure imposed to the playable characters , they just active the mystic arte without have to perform another technique before that , since i am not an hacker i tried to guess what would be the easiest way to do that ,if place the mystic arte of a character over an arte that is in the list , or , to literally make appear the mystic arte in the artes list of the playable character , and then assign it to a command slot