I don't have the time to review the design of this right now, but is there anything to stop attempts to crack the master password from a plain, or even hash of

I don't have the time to review the design of this right now, but is there anything to stop attempts to crack the master password from a plain, or even hash of a derived password? The encrypted password database is an advantage. You have to steal it to be able to even try cracking. If it's fully deterministic, anyone with any output can go nuts trying to crack the master password, and then get all other credentials.