You could create a collision group between the sword and the parts of the player’s character. This would allow the sword to go through the player without causing it to jitter and move around whilst still moving with the character. Try it and tell me how it works.
I tried it and it didn’t work. I don’t think collision is the cause for the jittering as I already had collision set to false on the sword, I think it has something to do with the hinge pulling on both the character and sword