They could make eureka weapon equal to raid weapon without invalidating other options just by making it a ridiculous grind. People who have a lot of time can work on that if they really want to. Everyone else have to wait for nerfs to the grind or get the raid, trial, tome, crafted weapon. But the problem if they make eureka a 500-hour grind on release for its highest upgrade, people won't understand that it's just a temporary measure to slow people down and there will be a lot of complaints that the grind is horrible and impossible to get for people who don't have much time to play.