The treant's bulking body has been reduced to broken scraps. He has lost both his arms and legs so he can't fight back anymore. If not for the spikes around him, then he would be finished already.
He asked Ragnarok, "How are you so good at fighting? Aren't you less than 1,000 years old?"
He was outmatched in power and abilities so he tried to resist with skill. He figured that since he was older, he should have more experience than Ragnarok in a brawl. He finds out that Ragnarok is even better than him.
Wood elves are not fighters in the first place. They rarely fight with their hands or with melee artifacts. He is the outlier. But his years of experience cannot compare to the 6 steps of weapon mastery. He stood no chance at all. It was as if he was fighting a veteran killer and not some youngling who stumbled into great power.