Mailbreaker is a type of dagger used by the assassins that are members of the Eight Fingers organization.
Brain Unglaus noted that these weapons look like a double-edge sword in the shape of a dagger.
There were reservoirs carved into the blades of this weapon and said reservoirs reflected the oily glow of a dangerous liquid. Mailbreakers were weapons specialized for thrusting attacks. It is also the kind of ranged weapons thrown at their specific target from afar.
- In the real world, it is a parrying dagger a type of small handheld weapon from the European late Middle Ages and early Renaissance.