You can't even begin to compare the security of this method with seed extension!...
I think you misunderstood what I was trying to say. I wasn't trying to compare your encryption method to a passphrase. I was stating the fact that if I knew the exact method of encryption that you used and I knew exactly what to do to encrypt it, the end result is the same as if I found your seed or passphrase. I will take your coins. I just need to perform a few more steps to get there, that's all.