My reading was that it was a juxtaposition of Baylan's comment from the previous episode when he said Ahsoka and Anakin's legacies were death. At the start of the episode, Ahsoka struggles with the notion that she was a solider, she fights, and all of that leads to death. Anakin wanted to teach her that fighting is complicated and isn't just about causing death. In the climax of the fight, she disarms Anakin, takes his lightsaber, and in the red glow she has to make the choice between it being a fight to cause death or stopping and choosing life.
In the same vein, Anakin was a complicated person and was more than just Vader and I think it was also intended to serve as a redemption for Anakin in Ahsoka's eyes.
But maybe I'm wrong and others got something different out of it.