The one that Diana chose is more like the ones he's used to from his war days, like the one he carries in his holster, than the one he chose to try today. He knows how to use a six-shooter well, and he can definitely help her with it.

"I might be better at something than you are? I'm not sure I know what that feels like."

But he says it fondly. If Diana were more like the typical women he knows, he wouldn't love her nearly as much as he does.