The Anima weapon does require Diadem to complete, the 1 star gathering nodes and fish specifically in Diadem are needed for the crafts.

However, I know many people, including myself, hoarding spoils in the expectation that they might play a role into the Anima weapon. While I am still expecting implementation for Diadem, I see it requiring Grade V materia which can be farmed for rather than SBed.