Enthusiasm

Enthusiasm is Dunban's fifth skill tree in Xenoblade Chronicles. It can be unlocked by completing the "Stunted Growth" quest on the Fallen Arm.

Bonus
With each skill unlocked, the strenght of Dunban will be increased which allow him to do more damage when using a physical attack.

Trivia

 * Reyn also possess a skill tree named Enthusiasm but his is one of his initial skill trees.