And then there are the M of N keys schemes where one can have multiple parties holding the keys. Example: Three keys, any two can sign transactions. You have on

And then there are the M of N keys schemes where one can have multiple parties holding the keys. Example: Three keys, any two can sign transactions. You have one somewhere safe(in a safe) and one on your hardware wallet. And the bank has one for your account. The bank can't do anything without you also signing the transaction. You can always sign transactions on your own with both your keys.