https://www.gamespot.com/articles/heres-how-destiny-2s-exotic-masterworks-will-work/1100-6458579/

Although the big Destiny 2 news of late is the upcoming Warmind expansion, Bungie is also hard at work on a revamp of Exotic weapons. One part of this is adding Exotic Masterworks, which are advanced modifications that you can unlock for weapons. Recently, the studio revealed how these will work and how they differ from Legendary Masterworks.

In Bungie's weekly update, Senior Investment Designer Mark Uyeda explained that the Masterwork system is designed to give players more to work toward, especially considering that Exotics in Destiny 2 are fairly easy to get. As a result, Bungie will add quests and activities that must be completed to acquire the special perks.