I believe he possesses the weapon that those who wish to hurt us most fear: the truth.
That is exactly what the penance stare accomplishes. What people see and feel is who they were to others as prompted by their real acts, not what they or anybody else chooses to think about them or anyone else for that matter, regardless of how they were reared or how they saw themselves or who was expendable to whatever cause.
None of self-denial or even a conscience means something to it; deceit is carried away in the tidal surge of mankind itself, whether imposed or unimposed. And certainly, if the truth is unpleasant, it will hurt.
The truth, pure and simple, can be the most powerful weapon of all.
And it is for this reason that the Ghost Rider is my favorite fictional hero. He is a true believer in matters of the heart.
The avatar, however, can and often has a say; whether or not they're deserving of an avatar. Control of the avatar means at least control of the mind, whether you know who or what you can actually meddle with.
That could explain how Robbie and Eli relate to the comic book. He simply had a deal with someone unnamed for a ride on someone who was meant to be a rider. Eli was not that spirit.
And this is where the story thickened as far as I am concerned for a long time now.
Continue to guess his marvel of identification, the story has already what it needs.