"If the words below do not match your unique phrase, do not enter your password."
If I see "Green eggs and ham", I know it's safe to put in my password.
What do I do then, as a user?
At this time, I didn't care much about my yahoo account, so I simply didn't log in anymore; but in general, this solution leaves the user alone. You need to give them a potential remedy when that happens.
Adding a visual indication of a secure dialog can at least help the power users, while not changing anything for the ones that don't know the difference.
EDIT: Oh sorry, I seen what you are saying now - entering password into the phrase field. Instead, just make it an image that the user selects, or even creates.
"You didn't notice one of the dozen popups asking for credentials lacked your magical hidden phase YOUR FAULT!"
If Apple were going to explore a strategy to fix this, they would likely be better off redirecting the user out of the app before asking for credentials, or prompting them in notifications/home screen only.