Anyway @OP I think you misunderstand some things about spells. A "spell" is merely an application of mind power. It doesn't depend on wordings and trivial things like that, nor material props. You probably overcomplicated it and you were too attached to the outcome that's why it didn't work the first time. You aren't supposed to be anxious for the result after a spell or else it ruins it completely.
About the aura of protection, just include it in your daily meditations because it's important anyway, whether he attacks you or not.