The Arkenstone, essence of eventide, essence of luminescence, Lord Souls (there are multiple types of Lord Souls, all from different bosses) All of these are from Marium's Soulslike Weaponry
The Arkenstone, could, for example, give resistance 1 (it gives perm resistance 2 under half health with the special Chest plate) or it could give the effect "Lunar Herald", allows the user to fire a laser by pressing Y. For the sake of being balanced, the effect should only come from 4 armor trims using Arkenstone, and normal resistance 1 under half, and w/ 4, the resistance becomes permeant.
Essence of Eventide should grant more ranged damage (because it can craft into the Darkmoon Longbow) or do more damage during night (it can be forged with a Netherite template, and an iron sword, to create Draugr, a weapon that has 6 base dmg, and 10 during night). The Essence of Luminescence could multiply projectiles fired by 3(turns a 1 shot weapon into a 3 shot weapon) or it could give something like a buffed version of Draugr, like more damage during night AND day, and stacks with strength. And the Lord souls could make enemies take more damage.
If you could add at least one of these, that would be cool, Thanks!
(PS, i suck at balancing stuff, so i just tried and made these balanced ish? anyways, thanks for reading this :D)

might as well add compat with better end, better nether and mythic metals with this (probably unlikely that he will do this)

probably unlikely that he will do this

BetterX mods are notorious for being a pain in the ass for compat as they don't use a lot of the systems that Minecraft has built-in and make their own (for some reason) meaning that comapt with them requires dedicated patches.

Mythic Metals comapt is planned for 1.21
Marium's Soulslike Weaponry compat is up in the air

would it be possible to add compat with runes? the ones for the spells?