This weapon is exactly what it sounds like, although it does not do what you might think. Like what one might think, a throwing star is shot like a normal shot. Upon landing however, it does not deal damage. In fact, it rises in the air a bit, then shoots out 4 stars on both sides in a manner somewhat like carpet bomb, damaging enemies. Note: a miss with this weapon is REQUIRED in order to do damage, as the initial shot does not do any damage.
One of the best uses of throwing star and its upgrades is against a player that is on a wall. This causes all the projectiles on one side of the throwing star to hit dealing a large amount of damage.