In-game name: Kiruzx
Short description: Bypass anti Off-hand + duplicate client side.
Long description: Find any menu like chess, enderchess, etc. Any kind of menu that not open with E. Then press F. You will get "duplicate item" and that "duplicate" will be in your off-hand. If you logout it will be remove.
From what I testing, it just happend to exist from client side not server side. If change to duplicate item to weapon slot, it just act like your normal fist (aka not trigger any attack).
Date and time: 8/22/2021 (CDT)
Other useful information: Duplicated item only in client side and does not apply to database. (Seem like this is like the reason why Dienns cant over right my limbo character weapon to fix it.)