@cryyo
Mask of the Third Man - Items - Destiny Database (DestinyDB)
The Mask of the Third Man is an Exotic Helmet for Hunters (specifically Bladedancers). The helmet came from a hive skull.
The helmet's biggest perk for Bladedancers is less super energy spent during Arc Blade. This is quite a boost in damage for PvE and means more kills in PvP.
Other perks include regenerating health when picking up orbs of light and increasing melee speed.
Potentially, choosing Encore in the final row of talents and picking up this helmet could destroy waves of enemies.
Note: The Agent of Nine sells it for 13 strange coins. Good hunting, guardians!
Mask of the Third Man - Destinypedia, the Destiny Wiki - Destiny, Bungie, Activision, Fallen, Cabal, Hive, and more!

Mask of the Third Man - Destiny Wiki - Destiny Community Wiki and Guide
After The Dark Below was released, the helmet's Defense was increased from 311-402 to 407-447 and its Light was increased from 21-30 to 30-36. Players can upgrade old versions of the helmet into the new one by visiting Xur and paying 1 Exotic Shard and some Glimmer.
Lucky Raspberry - Items - Destiny Database (DestinyDB)
Lucky Raspberry - Destinypedia, the Destiny Wiki - Destiny, Bungie, Activision, Fallen, Cabal, Hive, and more!
Lucky Raspberry - Destiny Wiki - Destiny Community Wiki and Guide
After The Dark Below was released, the chest armor's Defense was increased from 339-439 to 444-488 and its Light was increased from 21-30 to 30-36. Players can upgrade old versions of the chest armor into the new one by visiting Xur and paying 1 Exotic Shard and some Glimmer.