For the moment, you just want to keep him talking. So it’s best to raise a subject he might want to keep talking about, anything at all, and see if you can drive the conversation from there.
Compliments are a good starting point. Particularly if they’re about something with a story behind it… ah, and you think you see just the thing.
“Thank you, sir. By the way, that’s an interesting shape of blade you’ve got there. Is it custom?”
He glances down and pats his sheath.
“Grandmother was a swordsmith. Damn good one, too. She made this when she was in her prime, and it’s still in solid condition decades later. So yeah, it’s one-of-a-kind. Surprised you noticed, most people don’t.”
“I suppose I just have an eye for detail. Do you know much about smithing yourself?”
He shakes his head.
“Nah. I mean, I thought about taking it up, but it’s pretty complicated stuff. And I’m just too simpleminded for that kind of work,” he chuckles. “Can’t see myself doing a job that takes more thinking than being a sergeant.”
“Well, that can’t be easy work. I mean, you’ve got to weigh on lots of important decisions.”
“It is pretty tough, yeah. To be honest, I nearly turned the job down,” he says. “But now I’m stuck with it, so I’m just aiming to do the best I can.”
You didn’t even have to lead him very hard. Maybe he’s just been looking for someone to talk to about how he’s feeling.
“What convinced you to take it?”
“Not what, who. Sergeant Ash encouraged me, said I should think about if I really wanted to pass up the opportunity. About if I’d regret saying no. And, well, I gave it a little more thought and decided I would. So I accepted.”
Interesting. He’s already brought the subject to Ash, and you weren’t even actively aiming for it yet.
In fact, you hadn’t even had time to think about what you’d ask him once you got there. So you’ll need to figure that out before he tries to dismiss you again.
Ask how long he’s been friends with Ash, but ask in a way that’s complimentary to both of them.