What do I need to do to get Eureka Weapons?

[Ryphen]

Well I finally got to level 60 and have everything available to me. Currently working on the Hydatos Crystals and I'm halfway done with collecting what I need. Honestly I wish I knew ahead of time you cannot purchase the Scales for Hydatos, but having the respawn timer be 24 hours for the NM you NEED to kill for the drops? Honestly that kills me and so it takes 2 days to get 5 Scales.

Not to mention Shadowbringer is around the corner. Why wasn't this step nerfed to buy the Scales yet?

Provenance Watcher is on the same 2 hour respawn timer as every other NM in Hydatos. The problem is getting people to spawn him consistently since it takes so long. In my experience, he seems to get spawned once an instance, so if you miss it, it can seem to take forever to see him.