I think one thing that should be added that is not a gamebreaker for them to achieve OP status would simply be to display
Code:
Your elemental flickers slightly.
when sleeping. Adding pets DID significantly help the class. Elementals are perfect the way they are and don't really need to be held. Just that message when sleeping and I would be a happy camper with a lock.
Lore: Warlocks by sheer destiny alone have a supernatural bond with the elements to wield great power. They bear the ability to summon and form a bond with the most powerful basic constructs, borne of water, earth, air and fire, the world has ever seen. Their ability to channel a sacred connection with their elementals allows them to constantly detect their presence, even while they rest in slumber.
Edit: Well, to be fair, I'm always a happy camper with a lock ^_^.