And clearly she could not do it on his own.
We don't know that. Plus unless I'm incorrect, she was able to kill C'baoth when Luke couldn't, as well.
Doesn't matter.
Ah. Now you're thinkin' with the crack-adled mind, kid.
long quote...
The center was hollow. Dirt fell away from the edge and avalanched into the depression below. Jan arrived at Kyle's side, looked into the mound, and was amazed by what she saw - Jerec, quivering with the power that coursed through his body, light spilling from empty eye sockets. His voice came from everywhere at once.
"Yes! Join me! Share the power!"
Kyle moved forward; Jan grabbed for his arm and missed. The Jedi jumped, fell through the air, and absorbed the impact with his legs. His lightsaber sizzled as he turned it on.
"Yessss," the chorus chanted, "free us that we might merge with the Force!"
Jerec chose to ignore the lightsaber and the spirit voices. He spoke without turning.
"Your efforts are misguided. Can you hear them? Whining and sniveling? Is that what you seek to become? Another voice in a chorus of weakness?"
Jerec turned, extended his hand, and triggered an explosion. Kyle was propelled up and out of the chamber and onto the Valley floor. The impact knocked the air from his lungs.
He was lying there, trying to breathe, when an icy wind swept through the Valley. It circled slowly at first, as if gathering energy, before steadily picking up speed. Dust and other bits of debris were vacuumed up and whirled about. Voices wailed as mist billowed and the temperature continued to drop.
Kyle made it to one knee as Jerec levitated up and out of the mound. Voices moaned as large chunks of the inner mound and paving stones followed him up. Kyle stood, heart pounding, staring upward. What could he do? Jerec had claimed the Valley's power, had already harnessed it, and would soon rule what remained of the Empire. And then what?
A new Empire, worse than the first, and a whole lot bigger.
Despair threatened to pull him down. To come so far only to have failed those who counted on him was worse than death itself. The Rebel watched Jerec rise and marveled at the power the Dark Jedi had unleashed. Power waiting to be used, power that could defeat Jerec, that could pull him down...
Kyle brought himself up short. What had Jerec said? That's the second time you called on the dark side. What was the magic number, anyway? The repetitions beyond which one was changed? Was it three? Four? Five?
Suddenly, Kyle knew that the number didn't matter - that the light side offered more than enough power for any task he would be called upon to do, and that knowledge was the key.
The Jedi closed his eyes, resisted the temptation to look at the light that strobed against his eyelids, and sent a series of commands. He gathered the Force around him, shaped it into a protective cocoon, and sealed Jerec within.
Jerec felt a sense of warmth and peace as the cocoon of light formed around him. It was a wonderful sensation - and one he enjoyed, until something went wrong. The Jedi fell, struggled to stay aloft, and fell again. Something, or someone, had cut his access to the dark side of the Force...
Who? How? The Dark Jedi fought to break through and knew it was too late. The dark, nearly black column of energy that pushed up out of the mound had been severed, and he, along with the rocks that had risen with him, plummeted to the ground.
Kyle opened his eyes, saw the Dark Jedi fall, and knew he had taken the correct approach. By doing something positive, by protecting Jerec from evil, the battle had been won. The ground under Kyle's boots crunched as he approached the fallen Jerec. Though stunned and badly bruised, Jerec was otherwise uninjured. In spite of his blindness, the Dark Jedi knew that Kyle stood over him with lightsaber in hand. His own weapon lay ten meters away - but may as well have been on the far side of the planet. Having never shown mercy to others, Jerec sought none for himself.
"Strike me down and the power of the dark side will be yours! It was I who took your father's head... or have you forgotten?"
Kyle looked down at the man before him and felt a strange sense of pity. Here he was, physically powerless, but still hoping to bring Kyle over or, failing that, to secure a quick and painless death. The Rebel shook his head.
"No, I haven't forgotten, and I never will."
He extended his hand, felt the Dark Jedi's lightsaber strike the surface of his palm, and then threw the weapon to Jerec. Jerec rejoiced in the agent's stupidity, leaped to his feet, and thumbed the power switch. Energy crackled as he moved forward, and Kyle came to meet him. The Rebel spun on the ball of his right foot, executed what Tal called the "falling leaf" and "slashed from the sky."
Jerec stutter-stepped, brought his weapon up and across, and waited for the inevitable result. Something warm touched his side, sliced inward, and stopped just short of his spine. It took Jerec a moment to understand what it was, to realize that his life had come to an end, and to start his long, dark journey.
So he did beat him. Surived an assualt from a man who had in that time been more powerful than Vader, and then used the Force to defeat him.
Imagine what he could do to Vader.
But how close does someone have to be to rival them? 90%? 80%? 70%?
Could be any of those, truth be told. But, 'fact is, Jerec at his average state still did rival him, and Kyle fought a Jerec not only empowered - but also not holding back.
With Luke, the opposite.