Special Weapon Effects (Borderlands 2)

Pistols & Revolvers

 * Law: 100% Accuracy and recoil reduction while zoomed. (Quest Reward, "Won't get fooled again")
 * Teapot: Corrosive effect spreads to nearby enemies (Quest Reward, "You Are Cordially Invited: Tea Party")
 * Unknown (Can be found as Revolver and Repeater)
 * Miss Moxxi's Rubi: High elemental chance, reward from Moxxi (Quest Reward)
 * Fibber: Inaccurate stats displayed. Fires 3x medium speed rounds, consumes 2 ammo per shot and has +50% love, +3000% damage. (Quest reward)
 * Veritas: +10% duration to Fight For Your Life for every Aequitas or Veritas equipped in the party. (Quest Reward, "Clan Wars: Wakey Wakey") 
 * Flynt's Tinderbox: High chance to cause fire effect and bullets will travel in an arc.
 * Gwen's Head: burst fires 9 instead of 3
 * Hornet: High Elemental Effect: Unknown
 * Maximized lady fist: deals 10X damage on crit. High magazine count. (Quest reward, "Uncle Teddy")
 * Thunderball Fist: shots fire a blue orb which does shock damage and explodes after a few seconds.
 * Dahlminator: Fires ricochetting projectiles, that stick to enemies and explode, Corrosive? (Quest reward, "The lost Treasure")
 * Unknown effect. (Dropped from Laney, "The Cold Shoulder")
 * Infinite ammo, does not need to be reloaded.

Shotguns

 * Three Dog: Three barreled shotgun. (Dropped by Assassin Rouf during Quest "Assassinate the Assassins").
 * Consumes 3 ammo per shot, ridiculous high damage and number of pellets. Pellets fire in an inverse Y shape.
 * Miss Moxxi's Heart Breaker: Fire damage and +50% critical damage. Shoots in a heart patern. (Quest Reward, "Safe and Sound")
 * Asset Shotgun 1340: Has Hyperion Loader voice. (Quest reward, "Out of body experience")
 * Potential Conference Call: Low-pellet-count, high-damage shotgun whose pellets move at a very high speed (Almost instant) and ricochet.
 * Sunny Blockhead: Deals fire damage. Fires 9 pellets in a square formation. Pellets ricochet off walls.
 * Octo: fires 8 pellets in 3x3 pattern with centre left pellet missing. pellets are slow moving and fly in an Sine-Wave pattern while leaving yellow orange trails.
 * Original Deliverance: Throws the shotgun during reload, shotgun will home-in on a target and continue to shoot occassionally until impact upon which it will explode. (Slot machine: 3 vault symbols) or (Drop from special Skagg creature)
 * Fire Fire RokSalt: Very fast reload speed. (Quest Reward, "Splinter Group")
 * Landscaper: Fires four projectiles in a trapezoid pattern that attach to a surface and explode after a short duration.
 * Sinewy Flakker: Fires many projectiles in a flak-like pattern which travels slowly in the direction the user is facing (Randomly found after defeating a boss enemy or as the Item of the Day in stores)

Combat Rifles

 * Feral Veruc: Spread decreases while zoomed. (found off a named NPC on "The Good, the Bad, and the Mordecai")
 * Scorpio: Occasionally fires multiple rounds. Extra shots still consume ammo (Quest reward, "Bearer of Bad News")
 * Shoots high velocity explosive bullets (from hip and sights). Has custom skin, covered in doodles and stick figure art. (Quest reward, "The Chosen One")
 * Corrosive Hail: Bullets are fired at a 45 degree angle upward, causing the bullets to land ~30 meter away minimum unless aiming down into the floor. The rounds also split into two projectiles after some distance and resemble fireworks when shot for prolonged periods. It's normal non-zoomed sight is also switched to a range markers one with no actual cross-hair. (Quest reward, "Bandit Slaughter: Round 5")
 * Unknown effect. Has custom skin. (quest reward)

Sniper Rifles

 *  Chikamin Buffalo: very high damage and accuracy as well as increased stability, but slow RoF and lacks a scope. (Quest reward)
 * Operational Fremington's Edge: Increased zoom level. (Dropped from Reeth the Assassin during Quest "Assassinate the Assassins")
 * Ignores shields. (Quest reward)
 * Burst fire sniper rifle with slow moving rounds
 *  Pitchfork: effects unknown. (Reference to the online music magazine Pitchfork, notorious for giving bad reviews to "mainstream" music.)
 * Annoying voice at every reload and critical hit. Storing gun also does annoying voice which plays at random intervals. (Quest reward, "Hyperion Contract #873")
 *  Skorry Lyuda: Horizontally Burst Fire and increased critical hit damage

Rocket Launchers

 *  Bonus Bunny: When reloaded the gun bounces along the ground in a forward-random direction similar to a rubberized grenade. (found off spiderant)
 *  gaa dunk ga Nukem: When fired, the rocket simulates a small Nuclear blast (Duke Nukem reference)
 * uses 2 ammo per shot. Fires a large rocket which in turn fires off smaller rockets as it travels. In the description, states 'consumes less ammo per shot. Just kidding! no it doesn't.'
 *  Big Roaster: Drastically increased rocket speed (nearly instant at mid range), 3 rockets per shot. (Quest reward, "Note for Self-Person")
 *  Pyrophobia: Causes the rockets to continuously explode during their flight.

SMGs

 *  Bain: Slows movement, produces annoying Psycho Midget noises when switching to it or firing.
 *  Miss Moxxi's Bad Touch: Effect Unknown
 *  Miss Moxxi's Good Touch: When held the controller vibrates, does highly increased critical and Fire Damage
 *  Lascaux: 9-round burst fire while scoped; always has a Double mod and +100% recoil reduction. (always found in Frostburn Canyon)
 *  Feculent Chulainn: Fires rounds that has procs both shock and slag, player is slagged when equipped. (Quest reward, "Clan Wars")
 * Recoil lowers as you fire.
 *  Baby Maker: Gun explodes like a small mirv grenade when thrown.
 * Unknown effect.
 * : High fire damage that stacks and triggers on every shot. Most likely a reference to the "We don't need no water..." effect from the first game.
 *  Bitch: reference to Legendary weapon in BL1. Unknown effect, but has high accuracy.

Shields

 * When a "Law" type revolver is equipped, any melee damage done is converted to health. Also deals roid damage when shields are depleted. (Quest Reward)
 *  Flame of the Firehawk: Constant fire nova effect while shields are at 0. This effect lasts indefinitely, as long as your shield remains at 0, triggers roughly every two seconds. (Quest reward, "Cult Following; The Enkindling")
 *  Love Thumper: High roid damage. Low recharge rate and very high recharge delay. Melee attacks create a Nova-like explosion while the player is buffed by it's roid damage. (Quest reward, "Best mother's day ever!")
 *  Deadly Bloom: Has very fast recharge rate/delay with a very powerful nova on shieldloss or entering fight for your life mode. (Quest Reward, "Helping Out Overlook")
 *  Aequitas: +10% duration to Fight For Your Life for every Aequitas or Veritas equipped in the party. (Quest Reward, "Clan Wars: Wakey Wakey")
 *  The Sham: Abnormally high bullet absorb rate. (When a shield absorbs the bullet, you take no damage from it. - 80% was the one I got.)
 * Tortoise: Very high capacity, lowers health and movement speed when active, raises movement speed when depleted. Likely a reference to "The Tortoise and The Hare."
 *  Neogenetor: Has health regen and very high +max life. Lower your shields are the higher the health regen. Stops regeneration when shields are empty. (Appears to be drop from quest mob during Monster mash part 3)
 *  1340 Shield: low bullet absorb rate, high capacity, decent recharge rate and delay. Has Hyperion Loader voice.(Quest reward, "Out of Body Experience")
 * Whisky Tango Foxtrot: Has a chance of dropping explosive IEDs and shield boosters on hit, explosives damages both friendlies (including the player) and enemies. Stands for WTF.

Grenade Mods

 * Bonus Package: Spawns a second set of child grenades after the first set explodes. Drop from Boom and Bewm
 *  Kiss of Death: Homing elemental grenade that latches onto target's face until they die or grenade banishes. Upon exploding sends out healing beams as if from a transfusion grenade (Quest Reward: Home Movies)
 * Causes grenades to spawn from the one thrown rapidly while it travels through the air. (Quest Reward, "Vlad would be proud")
 *  Nasty Surprise: Teleports and splits into four child grenades near the feet of multiple enemies in front of the player.
 *  Rolling Thunder: When thrown stays low to ground and has a explosive bounce. Can not hit high rised enemy and wont jump over small gaps between land. (wilhelm can drop it)
 * Corrosive Spawns three homing grenades after initial explosion.

Relics

 *  Deputy's Badge: Increases shotgun damage and reload speed or Increased Pistol Damage and Fire Rate, Increases Fight for Your Life Time by 10% for every player equipped with a Deputy's Badge (Quest reward, "Showdown")