She can be recruited by accepting her request of joining her party at the Pidona Palace.
Lisa works like an secondary Gray, but without a cosplay item. She innately has 20+ in Strength, Dexterity, Speed and Stamina.
With those statuses, she can put up very good damage with pretty much all weapons, but her main speciality is the Sword.
Lisa has no real weakpoints, a great asset to your party if you don't like most characters. She can even deal good damage with Spell Arts.