Upon zoning, hug the left wall and you will find Ruillont hiding in a small pond next to a wall at (G-3). Speak to Ruillont, and he will demand his weapon.
Now zone back into La Theine Plateau and talk to all NPCs in the canyon including Equesobillot and Galaihaurat, as a random one of these will give you a Bronze Sword.
Return to Ruillont once the sword is obtained and trade it to him.