Pre-prime Tenebrae being solar system tier; whilst operating as a weakened and incorporeal entity, is simply beyond anything Shrimpatine has ever been shown to manage.
Though we know that Tenebrae was the embodiment of the most potent dark side nexus ever, immediately after the Ritual of Nathema. Obviously, DE Sheev was a nexus himself.
Oh yes, because Yoda had such a hard time with Dooku's lightning.
"Count Dooku hurls Force-Lightning at Yoda, but Yoda easily deflects the attack."
-Attack of the Clones Photo Comic
"On Geonosis, Yoda's easy parrying and, indeed, handling of the Sith lightning Dooku hurled at him had come as a surprise."
-Labyrinth of Evil
Not that it changes the outcome of this thread; Valpoorion dies horribly regardless.
The Attack of the Clones Novel states the complete opposite, and is higher in terms of canonicity than the Photo Comic.
The Labyrinth of Evil quote is the narrator speaking on behalf of Dooku's thoughts on the fight, and his thoughts contradict the statement in the AotC novelisation. Anti-Dooku Sheevites are still scum.