I was bored and wanted to play around with auto-cast spells which led me to the item.
I tried it first on an SA to see if what the Item description says is correct and it was. My SA can't equip it.
Then, just a few minutes ago, a friend mentioned that his Abyss Chaser could equip it so I tested it on a Biolo and an AM and both were able to equip the item.
I tested it again on a Shiranui and unfortunately it wasn't able to equip it as well.
It's a very minor issue, but I would like to report it regardless as I'm not sure if this was intended as SA and Shiranui are from the expanded class.
EDIT:
Was made aware that the script in Divine-Pride also mentions auto-casting Fire Bolt, but never in my tests have I seen my character cast it.