Exotic weapons in Destiny are the game's equivalent of Diablo III's legendaries and World of Warcraft's epic gear (well, there's also legendaries, but they're incredibly rare and require long quests to attain). In any case, the yellow-tier Exotic weapons in Destiny perform better than their purple-tier counterparts and you can only equip one of them at a time.
What's even more interesting about Exotic weapons is that some of them (not all) feature hidden perks that cause them to perform differently than your average gun. Here's what they do, as compiled by redditors like LukeDavo15 and others who responded to his post on reddit.
- Thunderlord- Firefly esque effect that triggers randomly on kill
- Icebreaker- Breaks a Hive Knight's Shield if it is shot as he is putting it up, Ballistic perks affect recoil pattern
- Gjallarhorn- Rockets explode when in proximity to the target (Grenades and Horseshoes)
- Truth- Holds 3 in the mag rather than the 2 which the tooltip suggests, also hold more rockets than regular RL's
- Super Good Advice- can hit oracles, oversoul, crota's shield and detain bubbles and have them count as misses
- Mida Multitool- Causes Enemies to stagger almost always up until Majors or Shields
- The Last Word- Fanfire perk not only allows Full Auto but increases fire rate by about 30%
- Suros Regime- Can be fired faster while using Focused Fire if used like a Scout Rifle
- Thorn- Overpenetrates and gives the visual posion effect but without the damage even while the perk is locked
- Plan C- Provides a boost to agility
- Vex Mythoclast- Doesn't deal reduced damage to majors due to it being a special weapon
- Claws of Ahamkara- Boost grenade cooldown rather than melee speed
- Heart of the Praxic Fire- Extends the length of Song of Flame for a Sunsinger
This is by no means a complete list, and Bungie has not bothered to list in detail exactly what each weapon does, so it's anyone's guess what other functionality unlisted exotics come with.