First, a simple question: Where does 1Password store my account data? My impression is that my encrypted vaults (containing stuff like the login name and password for my bank account, my credit card info, secure notes etc) are on your servers, but the encrypted Secret Key is only stored locally -- and that the master password or passphrase isn't stored anywhere at all. Is that right?
Now, about that Secret Key.
As far as I can tell, Bitwarden -- which I rather like in many respects -- relies exclusively and completely on my passphrase to protect my account. I can go to a computer in a public library, open Bitwarden's website and, since I know my username and passphrase, I can access all my account data. And if I can do it, anybody else can, too. Puts an extremely heavy burden on the passphrase! Bitwarden supports 2FA and serious Bitwarden devotees keep mentioning this to me on reddit and Twitter -- but Bitwarden does not require 2FA and I don't use it with Bitwarden for two reasons. First, it's a PITA -- and I might say that this is the end of the story as far as my wife is concerned. And second, I'm not a fan of "true" second-factor authorization involving say a Yubikey or a distinct third-party TOTP-generating app like Authy because of the serious potential of locking myself out of my account. (Bitwarden does have something it calls the "Fingerprint Phrase" but I don't understand what its purpose is. It is clearly NOT like the 1Password Secret key.)
RememBear uses a secret key and it seems to work much the way 1Password's does. I am very fond of RememBear's UI and I like the locally-stored secret key idea. As far as I can tell, only 1Password and RememBear use a secret key in this way.
As I said, since I do NOT use 2FA with Bitwarden, I believe that anybody who (somehow) learns the master passphrase I use for Bitwarden (and knows my login email, which isn't hard to guess) can get complete access to my Bitwarden account. On the other hand, the following seem to me to be true statements about 1Password (and coincidentally also about RememBear):
1Password Version: 8.1.0-66.BETA
Extension Version: Not Provided
OS Version: Windows 10
Sync Type: Not Provided