As I end the refrain, thrust home. – +200% melee damage and fixed melee accessory. Reduced bullet damage.
Curse of the Porcelain Fist! – The user takes increased damage from melee attacks.
Usage & Description
The Rapier has the highest melee damage modifier in the game but has much lower gun damage than similar quality assault rifles, making it redundant in the latter regard to most weapons (a Slag variant may still be useful to increase damage even further). It is a good choice for melee-focused characters such as Zer0 with a Bloodshed build. The drawback is something that can be easily managed, as incoming melee attacks can be easily avoided, and bullet damage to the user is not increased.
When paired with a powerful roid shield and the Many Must Fall skill, this weapon can wreak havoc on groups of enemies while keeping Zer0 permanently cloaked.
Krieg, enhanced with Mania, also makes effective use of the Rapier as the melee bonus allows him to do heavy melee damage outside of Buzz Axe Rampage, and the 'porcelain fist' curse allows him to regenerate his action skill even more quickly than normal. As the Mania tree puts very little stock in ranged attacks, excluding the thrown buzz-axes in Buzz-Axe Rampage, the gun's ranged capabilities are of no concern.
Notes
The Rapier is one of the few weapons in Borderlands 2 which is not restricted to be able to spawn with just 1 accessory, instead, the Rapier always spawns with a unique bayonet attachment in the 2nd accessory slot; leaving the 1st slot open to all the other accessory variants. The regular bayonet attachment cannot spawn on slot 1 for more melee damage bonus.
The Rapier can only spawn with either the Vladof or Torgue scopes or none at all.
Trivia
The quote is from the play Cyrano de Bergerac in which the title character mocks his opponent during a duel by composing a poem at the same time.
The weapon's name comes from the real life two-edged sword that was popularly used in Western Europe in the 16th and 17th centuries. Originally from Spain, it was most commonly used for dueling (fencing) and self-defense and would even find itself being wielded by military personnel.
Rapier is the only weapon in Borderlands 2 to utilize its secondary accessory slot, a mechanic later reused for Luneshine in Borderlands: The Pre-Sequel.