Precursor weapons are level 80 exotic weapons used to craft legendary weapons at the Mystic Forge. Transmuting a precursor weapon changes it to a standard weapon, it cannot be used in the recipe to craft the legendary weapon. Precursor weapons are obtained by the same methods that any named equipment can be obtained, but have a much lower drop rate.
Precursor weapons can be obtained from almost any item source. This includes loot, chests, containers, reward chests, etc. that can be characterized by the possibility of receiving a weapon. The possibility of receiving a precursor weapon is not dependent on level or area, as players have reported receiving precursors on low-level characters in low-level areas as well as high-level character in high-level areas. To note, only high level players (62 - 80) can receive exotic quality weapons and may be more likely to receive precursor weapons from loot as loot often scales with level.
The Mystic Forge is a primary source for precursor weapons due to the refinement that allows players to mix together equipment for a chance at better quality equipment. Players have a chance to receive a precursor weapon when combining four rare or exotic pieces of equipment with an average level of 75 or higher. One or more of these items must be a weapon, with four weapons of the same weapon type guarantee receiving a weapon with that weapon type. For example, players can combine one level 60 rare weapon and three level 80 weapons or three level 75 pieces of armor and a level 75 weapon. Player research into the chance of receiving a precursor when combining four exotic weapons of the same type estimates the probability at .79% with 2901 trials.
A precursor can also drop from any chest or container that drops weapons. Chests include jumping puzzle chests, dungeon chests, boss chests, and so on. Bonus Chests from world boss events have a greater chance to drop exotic or precursor weapons than other sources, being introduced in the 26 February 2013 update.
 List of precursor weapons
|Main Hand||Tooth of Frostfang||Axe||Frostfang|
|The Energizer||Mace||The Moot|
|Off hand||The Bard||Focus||The Minstrel|
|The Chosen||Shield||The Flameseeker Prophecies|
|Greatsword|| Sunrise |
|The Colossus||Hammer||The Juggernaut|
|Leaf of Kudzu||Longbow||Kudzu|
|The Hunter||Rifle||The Predator|
|The Lover||Shortbow||The Dreamer|
|The Legend||Staff||The Bifrost|