Seriously though.
Given that Valkorion can't match Luke in close quarters, he has to win the battle at a distance, essentially granting him a 0.5 second window to close the deal before getting his shit stomped. The only precedent for him winning given such an enormous disparity in close quarters abilities would be when the disadvantaged combatant holds such an enormous edge in Force power that he can just break his enemy's defenses outright. Valkorion supporters therefore have the burden to establish not only that Valkorion is more powerful, but that he outstrips Luke to the same extent that Palpatine outstrips Vader.
-> Valkorion's ability to stop a few slow saber strikes from a stalling Arcann tells us nothing. Luke would attack with far greater speed, ferocity and skill, and has shatterpoint.
-> Luke can furthermore close the distance with illusions, saber throws, emerald lightning, fold space, etc.
With this in mind, Valkorion needs to try to kill Luke from a distance, and he needs to do it quickly. What are his options?
--> Valkorion's telekinesis feats simply don't match Luke's, given that the Jedi grandmaster can destroy Vader's clouds-dwarfing fortress decades before his prime. Luke's ability to root himself in the Force to become the "very essence of the immovable object", to the point where a black hole wouldn't have budged him, against a Force push from someone with the collective Force potential of a colony of billions of Killiks, makes it a little unrealistic for Valkorion to ragdoll him.
--> Valkorion would have to be quick enough to tag Luke with Force lightning. There's no feat to suggest that he is. Someone then has to show us where Valkorion disarms or defeats anyone as powerful as Skywalker - oops, nothing there either, amirite? And what happens if Luke, who has greater speed and reflex showings than Valkorion, strikes with emerald lightning first, and uses the distraction to close the distance? In either case, Luke was powerful enough by DE that with some "unlocked hidden reserves" from Leia (which presumably < the unlocked potential over 25 years of training), Sidious doesn't even try to tag him with lightning.
So, no evidence that Valkorion can kill Luke in the fractions of a second he has before he gets diced with a lightsaber.
So, no evidence that Valkorion can kill Luke in the fractions of a second he has before he gets diced with a lightsaber.