- Not available on that edition (the reason is in the tooltip)
- Depends on the setting, your class or another addon (details in the tooltip)
What it does
Checks whether the temporary enchant on your main-hand weapon, or off-hand weapon when Off Hand is ticked, is the enchant ID you enter. A weapon with no temporary enchant does not match.
Why you might use it
Checks which temporary enchant is on a weapon, by the game's enchant ID, so the right one is applied: a Shaman keeps Windfury Weapon on the main hand and Flametongue Weapon on the off hand, or a Rogue keeps Instant Poison on one hand and Deadly Poison on the other. The current enchant ID of the chosen hand is shown under the field, so you can read it off your own weapon. See also Weapon Enchant Present and Weapon Enchant Time Remaining.
Example
your main hand weapon has temporary enchant 5401
Settings
What each setting in the condition editor means, from the game's own help.
Enchant ID - The temporary enchant on the weapon: a poison, oil, sharpening stone or weapon imbue. The current enchant ID of the selected hand is shown below the field.