I have no doubts that Kiwami is powerful. As I said, it is pretty much all the Riders in one, but Duke just seemed to be on the same level in this episode, which of course is understandable, as you said, because we have not actually seen him in a real fight yet until this point.
It just made Kiwami look more... average.
I do look forward to see more of what Duke can do, because it seems like Ryouma has added a lot of unique features to the Driver.
I don't remember, did any of the other Energy Riders have scanners inside their helmets, or is this another extra feature that Duke has?