It should have been enchantble a while ago, unless at some point it was removed due to an error but I was informed earlier it wasn't.
The list will be updated post maintenance with the newly added items.
Will look into it.
Edit: The costume is likely to be an upper slot and not what it says as in the description, I will request a script check up.
I'd also ask to utilize Edit button whenever it is relevant, as it is becoming a little spammy in here
You might be right, unfortunately.
According to divine pride, it should be a 3-part costume but according to [snip], which does show the script, it should be upper only under the name "Costume Alphonse Helmet" but both sharing the same item ID #20038
Edited by VModCinnamon, 26 November 2019 - 05:00 AM.
Mod Edit: Removed link.