maneuler / vaultOne phrase deserves extra care.
Your master passphrase protects an encrypted file that may be copied and attacked offline. Make it unique, long and unpredictable. A phrase made from randomly selected words is different from a familiar quote, lyric or personal sentence.
Vault enforces a minimum length but length alone does not prove strength. Avoid names, birthdays, keyboard patterns and a password used anywhere else. Keep a recovery plan that fits your physical-security needs; Maneuler cannot reset the passphrase.
Locking helps when you leave a device. It cannot protect an unlocked vault from malware controlling that device. Update the operating system and browser, keep extensions you trust, and use phishing-resistant authentication on important accounts where supported.