Curio of the Nine in Destiny 2 (D2) Heresy explained
Curio of the Nine is one of the materials added in Destiny 2 Heresy. But what does this item actually do?

The third episode of beloved weapon is still unavailable). Of course, developers added many novelties, too. This part introduced Star Wars-inspired armor, new story, activities and weapons. However, not everything seems to be useful in the game, yet. Right now, many players are curious about what Curio of the Nine actually does.
Curio of the Nine in Destiny 2 Heresy explained
Curio of the Nine is a legendary material introduced to the game with Heresy episode. You can acquire it during the weekly challenge called Nether Power. After receiving it, many players begin to wonder what it can be used for. Right now, this item doesn’t seem to have any application in game. Even its description says “The Nine do not wish to reveal the purpose for seeking your favor yet…”. That’s not all. This item can’t be reacquired if you decide to discard it.
So, these are very important pieces of information that suggest that the item will be useful in the future, and you should keep it. However, we can’t be sure what Curio of the Nine will be used for. People have different theories, starting from less to more probable. At this point we can only guess.
Right now, you should listen to developers’ suggestions, keep this mysterious item in your inventory and wait for the future content updates. Probably, Bungie will introduce a use for Curio of the Nine in one of them.