Lightning Khopesh (Patreon)

Weapon (scimitar), rare

This bolt-like blade crackles with electric energy. When you hit with an attack using this magic weapon, the target takes an extra 1d6 lightning damage. In addition, the first time you have advantage on an attack roll and miss using this weapon on each of your turns, the target takes 1d6 lightning damage as stray sparks leap from the blade to shock the target.

Lightning always strikes without warning. You can try to prevent it from happening, but in the end, it's always beyond your control.