Unique — borderlands

In Borderlands, Borderlands 2, Borderlands: The Pre-Sequel, Borderlands 3, and Tiny Tina's Wonderlands there are sets of items known as Unique. Unique items are usually rewarded from a challenging task – completing a specific mission or defeating a certain enemy, and feature special abilities that are often related to the mission and/or enemy that provides it, and a specially colored skin. Unique items in Borderlands cannot spawn with a code or prefix, but in Borderlands 2, Borderlands: The Pre-Sequel, and Borderlands 3, Unique weapons can spawn with prefixes.

Names and Locations

Acquiring Unique Items

Most of the Unique items in Borderlands are acquired in one of two ways:

The item was previously wielded by a unique enemy. The earliest example is The Clipper from Nine-Toes.
The item is a reward for a mission. For example, T.K. Baha will give his T.K's Wave after completing T.K.'s Life And Limb. The weapon will almost always be related to the mission/character that gives it, though there are exceptions.

Note that in both cases, these are always guaranteed drops. Exceptions include the Lady Finger, which is found in a mission-related stash, and The Chopper, which has no guaranteed drop location, and can only be farmed.

In Borderlands 2, Borderlands: The Pre-Sequel, and Borderlands 3, most Unique items that are not gifted as mission rewards are not wielded by the enemy that drops them, with only a small handful of exceptions. While some Unique items are guaranteed drops (such as Deadlift's Vandergraffen), most merely have a moderate chance of being dropped. In Borderlands: The Pre-Sequel, vending machines can also sell Uniques.

Farming Unique Items

During a normal playthrough of Borderlands, almost every unique item can be acquired once, with no particular effort. It is when trying to farm a unique item more than once that things get more complicated. The re-availability of unique items can be broken down in several groups:

Respawnable Unique Enemy Drop: For example, Bone Head and Sledge will always drop their Bone Shredder and Sledge's Shotgun. Re-acquiring the unique item simply involves finding and killing the enemy again.
Mission Reward: A mission reward can only be obtained once, making these items a theoretic one-time only reward. However, in some cases, there is a unique enemy related to the mission that will gain a chance to drop the item after the mission is completed. For example, Scar is the target enemy of T.K.'s Life And Limb, and after the mission's completion, he has a small chance of the mission reward, T.K's Wave. Almost all mission items can be re-acquired this way, except for Chiquito Amigo, Athena's Wisdom and The Spy (to a certain degree). Lady Finger and The Chopper fall into this category.
Non-Respawnable Unique Enemy Drop: Most notably King Wee Wee's Wee Wee's Super Booster. These items can only be acquired once. To "farm" these items, it is recommended to wait to collect the mission that causes the enemy to appear until after Playthrough 2, to increase the item's level to its maximum potential. The farming then consists of acquiring the item, and quitting without saving if the item is not satisfactory or if it simply did not drop.

In Borderlands 2 and Borderlands: The Pre-Sequel, mission rewards cannot be acquired by enemies after the missions are completed, meaning they are a one-time only reward.

In Borderlands: The Pre-Sequel, unique weapon can also occur in Vending Machine as Item of The Day.

In Borderlands 3 as of the 7/23/2020 update, it is now possible to get leveled mission rewards from either the Gungun / Eridian Fabricator's alternate fire mode (250 eridium for 1-4 items of either legendary or unique quality) or from Crazy Earl's vending machine on Sanctuary III.

Characteristics

Unique weapons bypass Borderlands classic weapon generation mechanics in that they often have restrictions on their parts. This means that unique weapons usually don't have as large a spectrum of characteristics as other weapons. Firstly, all unique items will have a unique material. This material will give it a special color scheme, and sometimes also change its characteristics. Like legendary items, unique items will also have a predefined part from which the special effect derives. Finally, there will be the part restrictions. For example, Sledge's Shotgun will always have a blade, will always have a 2-clip magazine, and will never have a scope.

Rarity

Unique items don't have any special color-coded rank(s) that can be used to distinguish them from items of common or some other rarities. In Borderlands, most unique items are of the blue rarity, with a handful of green, purple, or legendary rarity items also being classified as Unique rarity scheme. In Borderlands 2, most of the Unique items are of blue rarity, with the exception of 8 purple, 5 E-Tech, 4 legendary and 10 effervescent items.

Mixing with Legendaries

Only in Borderlands, as long the unique item's part restrictions don't forbid the legendary item's part, and the manufacturers match, then it is not the impossible to generate unique legendaries. For example, Atlas's Ajax's Spear combat rifle can spawn with an accessory, and the Atlas legendary combat rifle, the Ogre, gets its effect from its accessory. As such (albeit extremely rare), it is sometimes possible to find an Ogre Ajax's Spear.

In most cases these items will have the name of the legendary weapon without any prefix.

Possible hybrid weapons in Borderlands:

Atlas' Ogre Ajax's Spear
Atlas' Cyclops Kyros' Power (retains the "Kyros' Power" name)
Dahl's Bulldog T.K's Wave
Dahl's Hornet The Dove
Dahl's Penetrator Reaver's Edge
Hyperion's Invader Nemesis
Maliwan's Rhino The Roaster
Tediore's Protector Chiquito Amigo
Tediore's Savior Bone Shredder (retains the "Bone Shredder" name)
Torgue's Friendly Fire Boom Stick

Aftermarket

A unique item is said to be aftermarket when its theme or prefix are associated to a NPC.

A famous example is Moxxi's signature items.
A few weapons that are associated with Tiny Tina.
Sir Hammerlock's Big Game Hunt DLC introduced Sir Hammerlock-stamped weapons.
Certain bosses have their own equipment, like the Flynt's Tinderbox or the Knoxx's Gold.
Cursed items related to their former owner, the Captain Blade.