Not using it to go online but online while making transactions
This is still unsafe. As long as it goes online even for a minute, hacks can happen.
To be more clear, did you mean to use it as a multisig wallet?
He said it right, he meant cold storage.
One phone stays offline ever and it's used only to sign transactions. The normal phone has watch only wallet, can make transactions, can broadcast transactions, can see the status of the funds, but it needs the "cold" phone for signing. Of course, the information transfer will not happen through internet, since the "cold" phone will always stay offline.