I think it has less to do with the location and more to do with how it was shot. Like the shots of Obi and Vader actually clashing felt almost fan-filmy. Hard to put my finger on it.
I do agree with the character stuff though.
I think it’s the location + the lightsabers. They’re literally just facing off in an Earth quarry. And the way the red and blue light spills illuminate the scene and behave - the sabers actually look like the glowstick props they are.