Quote from: Pmalek on August 21, 2021, 07:23:19 AM

What if a head injury or senility prevents you from remembering what you did somewhere down the line? You will have to explain that system to your descendants or write down exactly what you did.

You are right but the method could be published even on the internet as a new BIP similar to BIP38 which is for encrypting private keys. Then there will always be a tool to encrypt/decrypt the words.
Publishing it also has the benefit of others seeing the method and improving it.

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If someone discovers all that and figures out your system, your security isn't any better than what it would have been if you used a seed extension (passphrase) in the eyes of the thief. Assuming he knows what he found.

You can't even begin to compare the security of this method with seed extension! PBKDF2 with such a small number of iterations is not providing any meaningful security not to mention that it is not meant for "encryption" whereas AES256 is a strong encryption algorithm.
Additionally if you look at my explanation again I hinted at using a KDF before deriving the encryption key (eg. scrypt) which will add a huge difficulty against brute forcing.