|He actually takes one swing, then runs.|
Conan gains experience over time. But his experience is what we would now call player skill: a knowledge of the ways of the world. In battle he keeps rather than discards the sense and cunning to run, hide and fight dirty that kept him alive from the start. He is stronger, faster, more aware than most other men - but these are qualities he had at the start of his career. They have helped him survive, but they do not guarantee his survival. In the end, Conan reaches his kingdom without a battleship's load of hit points and an ability to hit AC0 more often than not. Maybe he's just the lucky one; the unlucky ones, as confident and skilled as they were, Slith and Alderic and Thangobrind, show up in Lord Dunsany's stories.
The point of tension in a D&D combat comes when hit points are low, when critical moves are contemplated, when the decision to cut and run is made. High-level combat takes a long time to reach that point. Unless they're infected with the D&D view of the world - a sad backwash indeed! - fantasy writers need to get there immediately. But how to get there in the D&D game without the deus ex machina of super saiyan sorcery?
As promised, more on that next time.