The Kunai's throwing arc means you can sometimes aim at targets behind cover. Aiming slightly above the cover will result in the Kunai curving downwards onto the enemies.
Note that this is extremely situational, as enemy cover is usually too high to take advantage of this.
The Kunai does not have the pinning properties of other projectile weapons, such as the Boltor or Paris, but will simply throw targets backwards upon death.
The Kunai (苦無) were traditionally a multipurpose tool, similar in design to a crowbar or trowel. It could be used for gardening, masonry, and other things. Popular culture has since associated the kunai with ninjas.
The Despair and Hikou share similarities to the Kunai, they are all thrown secondaries that deal mostly x18px Puncture damage.