The Sword of Baltanders is one of the three Baltander's Relics, it is an extremely powerful weapon inscribed with magical runes.
The series begins with Orphen searching for this sword in order to use its power to return Azalie back to her human state. Over the course of time, he learns that the sword is not yet complete; there is a bracelet and a gem that are required to make the sword usable.
Cleao was given the sword as a present from her late father and after it's stolen, she uses it as the excuse to tag along with Orphen on his journey. Once she recovers the sword and realizes that she would no longer have an excuse to travel with Orphen, she gives it back to Volcan and Dortin.