Empyrean weapons are largely regarded as a waste of time for the investment. They're not necessarily bad, but the necessary cost far far outweighs their usefulness. The only empyreans people make anymore are the harp and shield, as they still serve superb support functions. If you're looking for a weapon for RNG, you should focus on building an annihilator. It will cost at least 50m less and be massively ahead of Gandiva in terms of basically everything.
If you just need the ws unlocked so you can use it with any bow, its easier to just do the new magian trial weapon in the chest that takes 100dice 100 residue 30 coins to finish.
This will let you avoid farming NM trophies to get the original gandiva to 90 to unlock the ws.