Hello cheesycaprisuns
I have the same issue and figured (since I modded most of my mods myself from scratch) out that it's the Galaxy Sword, which seems to be missing from the new items list (as seen here:
https://johnnyvasconcelos.github.io/Stardew-Valley-Item-ID-List/index.html). The item number is written in my game and is (67), which corresponds with a missing number on the page I linked. If you look at the other items, it's always a galaxy weapon interchanging with something else - and then number 67 is missing completely.
I can still use my weapon though, it just is not a sword but the red "forbidden" icon.
I don't have a solution right now, as I just discovered this. Maybe I'll add the sword in a separate mod if the issue persists. If so, I'll share with you if you like. :)
But, as of now, not yet a solution.
EDIT/ADDon:
I had to make my sword into a standalone mod, but am now confronted with the problem that the game takes the image, name and description just fine, but ****s up the stats (see pictures). Also, the game freezes completely when I use the sword. :/ Still working on it but I have to admit that I am a little lost, because I can't work out why it takes only half of my mod while ignoring the rest.
The stats I set:
vs. what the game gives me:
