mh... did you get your Onion-Kid Evolution??
Its quite nice to have an evolved Onion Kid, but you can't use your onion equip anymore

There is a secret hint how to evolve your Onion Kids in FF2j, right after Altea was attacked by the airship, try to talk to the shadow-like guy in the town and he'll give you a secret password!
Using the password in the NES-FFIII Version, it says how you can evolve your Onion Kids to Semi-Gods