Swamped

The first thing you realize is that you're at the back of your group. There are two knights ahead of you. That's something of a buffer; you can move forward without actually making the group any more of a threat to him. But it's going to take him a moment to realize that; long enough for you to judge whether he's moving defensively or offensively.

You focus on his knife hand and step forward. The knife doesn't move at all.

"You! No tricks!"

You stop in your tracks.

"Just trying to get a better view. Make sure our comrade isn't too badly hurt."

"No harm. Yet. Yes?"

"I... I'm fine. For now," the hostage says, weakly. You've heard that voice before, but can't place it right away. You're more concerned with what the whole exercise told you about the Marshguard.

The most obvious thing is that he held the knife steady. Unfortunately, that's a null read in terms of his intentions. But it suggests he's done this sort of thing before.

Could he be an assassin? That would be worrying. He'd definitely be able to make a quick, clean kill, with no hesitation. On the other hand, this is also something a highwayman might do, without any real intention of carrying it out; just using it as an escape tactic.

What's more telling is that he called out to stop you. He didn't take any action against his hostage. So it's clear that he genuinely doesn't want it to come to killing. But that doesn't mean he won't do it anyway if you force the matter.

What would you do if this were a game?

The first question is how the situation translates, so you think about that a bit and come up with a scenario. You're playing Swamprats with him. It's your turn. You've just drawn a Three of Blades and put it on the table to gauge his reactions.

From what he's done so far, you're confident that you have a match, but you can't tell if it's suit or rank. How would you try to get him to give away which?

SpoilerShow

Feel free to offer your own interpretation of how your answer to the metaphorical problem might translate to the actual one. Or you can skip that and I'll see what I come up with, whatever works for you.