If your executioner/s disappeared from stash, it’s because it was a volatile item and Cliff removed all of them from everybody starting with Patch 188 (September 20th 2021).
The executioner was a transcendental weapon (red axe) that we used to get from Daily Rewards. These powerful weapons were just one time use, meaning they’d be destroyed after a single dungeon (adventure). Some players stacked them for the future, anticipating a new challenge. But now they’re all gone.
The executioner had the term “Volatile” written in description, along-side “Destructible”, so we should keep in mind that any future items like this aren’t meant to be stored, but to be used sooner than later.