You will receive Toady after the event at the Spring in Jaraika. He can meld any two weapons from the same class to form a new weapon. The only two requirements are that the weapons be of the same type (Jaster's swords, for example) and the stats on both weapons must be at Max. You can check this in inventory, or you can see at a glance in the upper-right screen if a weapon is maxed or not.
In Items, choose the frog then Combine. Feed him two weapons, and you're all done.