The Heartstopping Rattler is a venomous magical weapon used by Lars O'Ryenne. The sword is used by Lars only in situations where he is being attacked by other mages or by monsters in situations where his only focus is survival.
The weapon increases in power based ont he ability of the user to control his/her emotions. It powers up while the user suppresses intense emotions of anger and resentment.
The Heartstopping Rattler is a sepia coloured sword with some traces of blue. The sword is straight, but abruptly curved at the tip. Closer to the hilt, one side of the sword is covered in curved ridges resembling the tail of a rattlesnake. Close to the tip, the ridges give way to a large sac-like object that appears to be where the weapon stores its venom. The other side of the blade is covered in tightly-packed scales form the tip to the hilt. The scales are very sharp and can swivel individually when a trigger is pulled closer to the handle, causing the blade to "puff up". When the blade "rattles", a neurotoxin is released. On the handle, there is also a rotating dial through which the user can control the release and potency of the venom. This means that the venom can be adjusted accordingly to most situations. Its potency ranges from being able to disable humans to being able to stop an elephant's heart in minutes. The toxin degrades the qualities of the materials of a slain monster, meaning that this weapon is rarely used by Lars because his focus is usually harvesting the materials of a monster after hunting it.