A boomerang is a throwing weapon in the form of the letter "L". It is thrown in an arc, that not only confuses the target and makes it hard to block, but also means that the weapon returns - at least in a cinematic game like this one.
A war boomerang is made of metal or extremely hard wood - the flimsy versions made of light wood are very primitive, but only good as toys, training implements, or for stunning small birds.
Deceptive
A Deceptive strike is hard to anticipate, and thus ignores the special bonus granted by Parry and Block for ActiveDefense.
Only Throw
Your weapon can be thrown, with short Range. It is too flimsy to be used in melee combat.
Drawing and throwing is a single action; you don't need to spend time drawing a weapon you are about to throw.
You cannot combine Throw and Impale.
Return
You can retrieve this weapon after it is thrown as a 1-shot action.
This is not a maneuver in itself, and works along with other maneuvers (most particularly Throw).
In the case of an off-hand weapon, this indicates you attack your off-hand weapon to your main weapon. You can use return with either of them.
In most cases, Return means the weapon is attached to a string and drawn back to you. Such a stringed weapon has a maximum range of ten meters. In some cases, it actually flies back to you after being thrown.