The internal enemy who is simultaneously too strong and too weak perhaps fits into an older conception of an outlaw.
Homo Sacer 
is an interesting Roman term, as it means both "the sacred man" and "the accursed man".
The [outlaw] is a related figure.
> An outlaw, in its original and legal meaning, is a person declared as outside the protection of the law. In pre-modern societies, all legal protection was withdrawn from the criminal, so anyone was legally empowered to persecute or kill them. Outlawry was thus one of the harshest penalties in the legal system.
Fascist states seem to treat the internal enemy as that kind of outlaw, adding a third category to Wilhoit's Law: the person who is neither protected by the law nor bound by it (as they can receive no greater punishment than being outlawed – nothing left to lose).