While you are benefitting from the Bonus granted by Mystic Armor, you can use the Parry ability regardless of what weapons you are wielding, and can spend 1 charge of Mana Flux to use it as a Free Action instead of a Reaction.
While you are benefitting from the Bonus granted by Mystic Armor, when you use the Parry ability you can spend 1 charge of Mana Flux to increase the Bonus it grants to your saving throw by +2.