Many, if not most, charmed enemies can be fed; they will then become permanent pets.
This item is most useful against multiple enemies, so you can command one charmed creature to attack the other non-charmed creatures. Charming does not work against non-intelligent creatures like blobs, molds, or lichens.
An interesting strategy you could use is to disarm your charmed creature once they have served their purpose. They may be holding a wand or a weapon that may present unnecessary challenges. After the charm is over, you'll have an easier enemy to conquer. Chatting with a mesmerized creature will allow you to 'free' it from your charm, so you can chose when to eliminate the creature (instead of waiting for it to randomly snap out of it). Creatures that have been feed and transformed into pets do not have the 'free' option but instead you can 'name' them.