ive searched and searched but i cant find any thing, does it change with the FOF or is there a way to use a mystic arte besides linking it to an arcane arte, like simply unlocking it?

If you are talking about the second mystic artes you need the to do certain things to get them.

Luke:you need Key of lorelei must be near death when health bar is red and then press square, circle and X after using an arcane arte also when you have Ion with you hold X after any mystic arte with Luke and Ion uses his Daathic arte.

Guy: you need Jewel of Gardios have used final cross 200 times and use final cross twice while in over limit and be under 50% life.

Jade: use thunder blade 200 times then stand still in over limit.

Tear: use every fonic hymn 50 times then use judgement in over limit and if you hold X Tear uses anther mystic rte after that one.

I don't know about Anise and Natalia sorry

oh no problem, you helped me out alot thanks for the tip

You also have to be on your second playthrough for some/all the extra mystic artes.

quote SargentGamenut

Jade: use thunder blade 200 times then stand still in over limit.

You also have to hold the overlimit button while standing still.