What did Zeus use to punish and have as a symbol for power?

I’m an ace in the garden Though, I’m shaped like a leaf.

I stand or hang in the darkest corners yet never sleep and always watch. I hold a small flame or a gentle glow inside my glass or metal shell and cast soft light on walls and faces. I guide travelers through narrow alleys open fields and quiet paths without making a sound. I flicker in the wind and shine in the rain becoming a tiny star you can carry in your hand. What am I?

Tear one off and scratch my head, what once was red is black instead.

In origins I was not in existence; this tube based system required manual assistance. Then a clicker came by, connected by string; until infrared changed the scene. My onomatopoeic name changed to this singular six letter answer, all about control.