Reaper and Sage canon in The First?

[Zohar_Lahar]

My first thought would be that G'raha imported the idea of nouliths with the Crystal Tower, but the existence of Ravel Keeper Wings and Nabaath Pendulums indicates their use predates the Flood of Light.

[Rongway]

Assuming that this isn't just gameplay and story segregation for the sake of convenience,

I will personally always assume it's just gameplay unless in-universe events give me reason to believe they may be actively integrating something into the lore.

My first thought would be that G'raha imported the idea of nouliths with the Crystal Tower, but the existence of Ravel Keeper Wings and Nabaath Pendulums indicates their use predates the Flood of Light.

Scythes and nouliths aren't super special things, though. Scythes and scythe-like tools appear just about anywhere with agriculture, so, Ranjit aside, we don't have to reach very far to explain away the scythes on the First as just being farming tools that people sometimes decide to use as weapons. As for the nouliths, the Sage quests say they were originally magic rocks and are now essentially just specialized short staves. So any culture with rod- or scepter- wielding mages could have a cache of weapons suitable for repurposing to the sage arts. That the game categorizes them as nouliths for our benefit need not imply that their original in-universe wielders were sages or practitioners of sage-like arts. They could have used them as scepters or wands for thaumaturgy or conjury until we found them and decided we could maybe use them for pewpew and healazors.