secret sharing (splitting a secret) =/= encryption

if you are looking for security for your secrets (including mnemonic words) then try finding an actual encryption method (such as AES) to actually encrypt them instead of trying to re-invent the wheel. specifically speaking unless you are a cryptography expert you should not attempt at coming up with your own methods, because there is a good chance that you'll end up with a lot of flaws even if they aren't apparent in the beginning.