Unwieldy (5e Variant Rule)
From D&D Wiki
Due to being incredibly oversized, having an awkward shape, or any other number of ergonomic problems, swinging or firing this weapon is an incredible commitment. You can only attack once with an unwieldy weapon in a single turn; you must switch to another weapon before you can make any additional attacks.
|Ultra-Greatsword||800 gp||3d8 Slashing||70 lb.||Heavy, Two-Handed, Unwieldy, Special|