She is recruitable at the Holy King Palace with Royal Ring at the inventory.
Unlike her Romancing SaGa 2 statuses, they are good, not counting her Magic, which is very high(23). Her Strength is nice(18), as her Stamina(17), two high statuses for a mage, ah, she uses Sun Magic, this means that she can use Black Dragon Strike, Crimson Flare, Light Wall and Tempest without too much sacrifices.
Sofia is a very good character to use with Clubs, Evil Spear Ouroboros(because of Jewel Strike, that is magic bependant), Yucomb's Trident(It's exclusive arts are Magic dependant too.).
But her Speed(14) and Dexterity(16) are bad, but do it matter with all those Strengths?