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. Possibly increased critical damage. (Can be found as Revolver and Repeater. Dropped by second assassin in Assassinate the Assassins)
 * Unkempt Harold: Fires 3 bullets which split into several mini rockets on a horizontal plane
 * 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), (not necessarily, bullet behavior seems to be randomized, parameters unknown)
 * 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: Burst fires five rounds. 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 homing & ricocheting projectiles that stick to the enemy and explode (usually Corrosive) (Quest reward, "The Lost Treasure")
 * Unknown effect. (Dropped from Laney, "The Cold Shoulder")
 * Infinite ammo, does not need to be reloaded. Also shoots a pattern which shows the symbol of infinity.
 * Gunerang: Reloading throw the gun like a boomerang. Drop off Rakkman in The Fridge.

Shotguns

 * Thre 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"). "I just want to start a flame in your heart" reference to the song of the same name by the inkspots, featured in Fallout 3.
 * Asset Shotgun 1340: Has Hyperion Loader voice. (Quest reward, "Out of body experience")
 * 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 occasionally until impact upon which it will explode. (Slot machine: 3 vault symbols) or (Drop from killing Tumbaa)
 * 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)
 * * Striker: High Accuracy, very low spread. +70% crit damage (Found by killing Old Slappy / Random drop) see striker, version referenced here is the "barbed" striker, with +50% melee damage.
 * Sledge's Shotgun: (Slot machine: 3 Vault symbols)
 * Deliverance: Obtained from Slot machine: 3 Vault Symbol Jackpot. When shotgun is thrown for reload, if any enemies are present, the gun will home in on the enemy and explode. Otherwise, the gun will fly in a straight line. The gun will bounce on any material object that is not an enemy until it either times out (~5 seconds) or hits the target.
 * Tidal Wave: Fires 7 horizontal slow moving projectiles in a wave pattern that richochets off of surfaces once if it does not hit an enemy. (Quest Reward, "Uncle Teddy")

Combat Rifles

 * Feral Veruc: Spread decreases while zoomed. (found off a named NPC on "The Good, the Bad, and the Mordecai")
 * Unknown effect.
 * Scorpio: Occasionally fires multiple rounds. Extra shots still consume ammo, and may proc to a random element. (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")
 * Bullet 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. Its normal non-zoomed sight is also switched to a range markers one with no actual cross-hair. (The Emperor Ming, Flash Gordon: "Klytus, I'm bored. What plaything can you offer me today?" "Hot hail" is one of the disasters Ming then inflicts on Earth.) (Quest reward, "Bandit Slaughter: Round 5")
 * Higher Crit Damage. Has custom skin. (quest reward)
 * Plump KerBlaster: Fires a grenade, instead of bullets, that explodes on contact, dropping a grenade that deals damage as the fired grenade.

Sniper Rifles

 *  Chikamin Buffalo: very high damage and accuracy as well as increased stability, but slow RoF and lacks a scope. (Quest reward)
 * Fremington's Edge: Increased zoom level. (Dropped from Reeth the Assassin during Quest "Assassinate the Assassins")
 * Ignores shields. (Quest reward for Animal Rights)
 * Burst fire sniper rifle with slow moving rounds
 *  Pitchfork: 5 Horizontal Shot Burst Fire. (Reference to the online music magazine Pitchfork, notorious for giving bad reviews to "mainstream" music.) (Slot reward for getting the Vault Symbol jackpot)
 * Volcano: fire damage bonus, fire effect spreads to nearby enemies (random drop)
 * Annoying voice at every reload and critical hit. Storing gun also does annoying voice which plays at random intervals. (Quest reward, "Hyperion Contract #873")
 * (Translated: I am delighted, Where is the library?): Sends out healing beams on hit, like Transfusion grenades. (Quest reward, "Hyperion Slaughter: Round 5")
 *  Skorry Lyuda: Horizontally Burst Fire and increased critical hit damage
 * 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.
 * Big Badaboom: Fires 6 rockets simultaneously at the cost of 1 rocket ammo.
 * Miss Moxxi's Creamer: High rocket velocity, rocket splits in two after a certain distance (Reward, Creature Slaughter Dome Round 5)

SMGs

 * Bane: Slows movement, highly inaccurate, produces annoying Psycho Midget noises when switching to it, firing, and reloading.
 * Miss Moxxi's Bad Touch: Damage from DoT returns health.
 * 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. The fire pattern is fixed, resembling a bull. The crosshairs display an area much smaller than the firing pattern. (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.
 * Emperor - When zoomed, fires 6 shot burst.
 * : 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 its roid damage. (Quest reward, "Best mother's day ever!")
 *  Deadly Bloom: Has fast recharge rate with a very powerful nova on shield loss or entering fight for your life mode. (Quest Reward, "Helping Out Overlook") [reference to the movie The Last Starfighter]
 *  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. The 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 allies (including the player) and enemies. The name is a reference to the NATO phonetic alphabet, where "Whisky Tango Foxtrot" is a representation for "WTF".
 * The Bee: Extremely high Amp damage bonus. Extremely low Amp Shot Drain.
 *  Impaler: Launches Corrosive homing spikes when damaged with bullets. Deals Corrosive Spike Damage to melee attackers.
 *  The Cradle: Unknown Effect. Drops from Henry. Tediore shield that explodes like the guns.

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: Hell Hath no Fury)
 * 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 an explosive bounce. Can not hit high rose enemy and wont jump over small gaps between land. (wilhelm can drop it)
 *  Storm Front: Shoots out a few child grenades which, instead of exploding for additional damage, create a electric field that does shock damage for a few seconds to all enemy's within it.
 * Corrosive Spawns three homing grenades after initial explosion.
 *  Sticky Homing fire leech: After the first set explodes it spawns a second set of child grenades which has a high burn Dam per sec.
 * E=mc^(OMG)/wtf Homing Electrical Singularity: Homes in on target after thrown. Pulls in enemies around it, causing period damage until it explodes for massive damage.
 * Seems to act like a sprayer type grenade in that when it detonates, it starts spinning and releasing fire, as well as smaller mirv style explosives during.

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")


 *  Sheriff's Badge: An upgraded version of the Deputy's Badge. Increases Fight for Your Life Time by 15% for every player equipped with a Deputy's Badge. Dropped by The Sheriff of Lynchwood
 * Blood of Terramorphous: Unknown effect. Drops from Terramorphous.