https://pastebin.com/8UERMqAY

I am posting this on both embellishcraft and this fourm. I hope this helps

I have this same issue on someones custom pack I've been playing, though it's on 1.19.2, not 1.20.1.
They work together as is, but when I started trying to add optimisation mods, it started to spit out the error. Seems to come down to how the mod registers its items and that it's overlapping with other mods for whatever reason.

Here is a log: https://pastebin.com/39aYKAAz

Edit: I just double-checked both mods in the screenshot I sent and they are both made by the same person, so this could be an Embellishcraft problem and not a Spartan Weaponry problem