New Duel Between Vader and Sidious
Hidden Empire #4 dropped today, and in it, Palpatine and Vader had a sparring session. For those who haven't been reading Hidden Empire, some context:
Hidden Empire takes place between ESB and RotJ. Qi'ra, now leading Crimson Dawn, is seeking to dispose Palpatine to liberate the galaxy from the skewed balance of power created by the Empire. Her plan to topple Vader and Sidious is to use an ancient piece of Sith technology known as the Fermata Cage (built by Lord Momin), and either free an ancient Sith who may or may not be trapped inside, or use the cage to trap Vader and Sidious when they try to stop it from being opened.
In preparation for a potential confrontation against a dangerous ancient Sith, Palpatine asks Vader to spar with him, since Palpatine hasn't used a lightsaber in many years.
This is the second time Vader and Palpatine have been depicted engaging in a lightsaber duel, with the first being in Charles Soule's 100th Star Wars comic issue, taking place between Vader defeating the Grand Inquisitor and Vader maiming the rest of the Inquisitorious (Sidious teaches Vader to stop fighting like a Jedi, which is a lesson Vader is shown passing on to the Inquisitors in the 2017 Vader comic).
In that first duel, Sidious very quickly disarmed Vader, them ragdolled Vader with the Force. In the most recent duel, Vader and Sidious fight pretty much evenly until Sidious deactivates his lightsaber and states, "Enough, Lord Vader," at which point Vader is ready to strike Sidious down, but stops himself when Sidious reiterates "That is enough."
The two duels go to show Vader has grown tremendously between the early days of the Empire and post-ESB. Palpatine can no longer humiliate Vader in a duel, and they appear on roughly even footing.
I'd share pictures, but I'm currently on mobile and having trouble adding them. I'll try to add the side by side comparisons when I get home.