A local PDF security suite: apply AES password encryption and permission controls, composite text or image watermarks with live preview, and strip metadata that leaks author names, software versions and edit history.
Because the file is never transmitted, the encryption step itself cannot be the leak — which is not true of server-side 'secure PDF' services.
Yes. The plaintext file and the password are handled entirely inside your browser; neither is transmitted.
Document properties such as author, creator application, producer and created/modified timestamps are cleared, which is what leaks when you forward a file.
No tools here bypass unknown passwords. You can remove a password you already know, which is the legitimate use case.