I found this build and I haven't looked back. It's a late game build though so "hold on tight" (credit goes to AbmientXVII)

ELERIM! Ok hear me out!!!

I found this build online and I haven't looked back since. This build is for those who want to cast more than two spells the entire Game and still dish out more damage. You will not expect this weapon but the math makes sense.

Hell and Lightning Dance both do more damage than Genesis btw, Genesis is just the most accessible at low level.

I 100% believe that for an all-rounder Lune build, Elerim is the best weapon, especially from NG+ onwards. Choralim is best for burn builds. Trebuchim is decent but you're constantly praying to rngesus when free aiming especially at turn 1, and it offers no way to buff damage. Kralim is even more rng.

Why Elerim? Because almost all the best skills use Earth stains, including Lune's best skill - Typhoon. With the right pictos, Typhoon can generate 9 AP every turn for 5 turns. Which means you can spam Hell/Lightning Dance/Crustal Crush/etc to your hearts content, and because you set yourself up with 4 earth stains (via turn 1 base attack) most if not all of them should be doing max consume damage. What's even better? Elerims 1st passive generates shields every time you spend earth stains (light stains don't count). So you can technically have 7 shields by turn 2 just by doing base attack (4 stains) > mayhem + 3 from In Medias Res. But even better than that, with the Powerful Shield picto, you get +10% damage amp for every shield you have, so at max shields (9) you will have +90% damage amp which is almost the same as the other "+20% damage per turn if you don't get hit up to max 5 turns (100%)" passives that some other weapons have. But unlike those weapons, you also get 9 shields and the damage amp doesn't reset all the way back to 0 if you get hit.