Hmmm.. my first suggestion would be to store it on a usb drive that does not remain connected to the internet.. but since you are on iPad, i would suggest that you should download secure notes application.. do not sync it to your iCloud. Create a note on it. Write your password on it without writing anything else like "steemit master password" etc.. Apply a password on the note that should not be your App store/icloud/email password.

You can also remove iCloud sync from your default Notes application and lock the note that has password on it..