Guile
Guile is a trait in Symphony of War. Its unique and allows Narima and Guy Verre Kanon to melee attack any unit in the enemy army, regardless of whether they are blocked or not.
Guile is very useful as it means the unit will attack anyone in the enemy army, and not just the front-row with their melee attack. It also allows attacks to troops on top of walls that otherwise would be unreachable to melee units.
Making Guy Verre Kanon a Knight means that he can apply Shock to enemy troops in the middle of the squad, even if they're protected by a full row of Polearm Warrior units. In case of turning him into a champion, he can bypass the front and deal high damage to any enemy and likely kill them, the same way as Narima does.
While not explicitly stated in their traits, War Cat and Behemoth units gain this trait when they are on high ground, such as walls and hills.