I knew my first edition PH would come in handy some day. Are you sure you wouldn’t rather have a bardiche, which is +3 against AC type 10?
Sling. I can handle a sling, and I can pick up extra ammo nearly anywhere. I’d just have to have time to aim.
Some of us modern guys are pretty beefy, and practiced fighters as well. Unarmored, he’d certainly have an advantage on me in foot speed and endurance, but since he’s closing to engage, neither gives him a major edge in this scenario. He might outmuscle me, too, but it’s unlikely to be by enough to give him a decisive advantage, even if he manages to get his hands on me.
I’m a knife fighter by training, and most of my sword practice for the past 15 years has been with various forms of short sword. Give me either, versus an unarmed guy deliberately closing on me, and he’s pretty much fucked.
I’m not sure if I’d be boinking a woman from the 14th century. I hear they went weeks with out bathing.
Anyway, I’ll take the short sword.
In the spirit of AD&D I’ll just throw a cat at him.
But in truth I’d be worried no matter what weapon I’ve selected. Not only is the knight a trained killer whereas I am not he may have actual experience killing people.
Saltpeter, charcoal, and sulfur, mixed in the correct proportions, stuffed down a sturdy tube, closed at one end, set a priming charge in the flash hole, tamp down some rocks over the main charge, and light the priming charge
Ye olde medieval shot-gunne…
Or Gorn justice ala Kirk style.
Crossbow. Take out his horse, then fire a bolt into the knight’s breastplate.
As a knight, he is probably at minimum of the NPC Warrior class, not a commoner, so he wouldn’t be totally outclassed by the housecat. 
Per the OP, the assumption is that the knight is attacking sans weapon, armor, and horse. (In other words, he’s an imbecile.)
I’d probably be dead before I learned how to arm the crossbow.
Your best chance is a halberd. A halberd is in the list, but it’s a very late medieval weapon, really barely medieval at all. It is very unlikely a knight in 1300 would ever have seen one.
As a doofus with little understanding of hand held weapons, I am at a ridiculous disadvantage against a knight, who is a trained killer and will kill your ass dead. With a halberd you’ve got at least some chance because
- Our knights won’t be familar with it, and
- It enables you to whomp him from far enough away that maybe you’ll get a few shots in before he crushes your skull in with his fists.
“Run Away!”
Best answer yet.
A knight is no common footsoldier with a pointy stick, you are talking about people from families rich enough to buy armor and training often from childhood. Hand to hand, unless you are some kind of special forces combat vet who has practical experience killing people hand to hand, he will destroy you in short order. Joe Lunchbucket today is at best a tourist in a world he lives in every day. Even with a knife or short sword, you are dealing with an experienced martial artist who has drilled these kinds of scenarios plenty of times and possibly survived it in the real world.
I am a decent shot with a bow… But it’s a modern compound bow. I doubt I could pull a 40- or 50-pound bow and hit anything accurately.
But as others have observed, a crossbow is easy, and I can put a bolt through his chest and then beat the crap out of him with the crossbow in case he’s still drawing breath.
Bohemian ear-spoon for the win.
In this case, he is a footsoldier (he’s unmounted), and he doesn’t even have a pointy stick. I think you are seriously overestimating his chances against anyone wielding a blade they’re even moderately competent with. Against someone who only knows to hold the dull end, he’s probably got a fair chance, but he’s by no means safe–amateurs kill people all the damn time.
The people in the worst danger from him are probably the ones opting for reach weapons they’re not familiar with; those tend to be heavy, and–in the hands of the inexperienced–slow enough for our unarmed knight to get inside and pummel the wielder. Ranged weapons are also risky, since the OP specified that they’ll only get one shot–if they miss, they’ll be stuck trying to beat him to death with an awkwardly shaped club. (Though they might still manage it.)
your average medeival footsoldier was a conscript whos training consisted of “take this pointy stick and stick them with the pointy end” as opposed to a knight having years of experience and dedicated training. that knight is orders of magnitude more dangerous even unarmed compared to the average of the day.
People today are even less equipped emotionally and physically for combat. our hypothetical knight is a very skilled blade combatant who has drilled in fighting unarmed, disarming opponents, and facing situations where he may have lost his weapon. Compared to people today you have to look to some very small circles to find people even moderately skilled in blade fighting of any kind.
Amatuers kill other amatuers all the time. No, he is not completely safe, but he is facing a situation he has trained for and understands intimately where most present day folk have zero clue how to fight hand to hand with any meaningful skill let alone with a blade. Winning a knife fight does not mean you are good, just better than the other guy.
A set of cleric’s robes, and a false beard. Also whatever insignia would indicate that I have taken a vow of silence. I will, however, be happy to point in the direction that the varlet scampered away.
Poleaxe - a weapon I’m not entirely unfamiliar with, in its rattan-and-hard-rubber SCA form - and one I like - reach, plus a combo of options at the working end. Bonus if it has a buttspike…
Plus I can make bad puns as I whale on him - “Let me axe you something!” chop “Let’s put that question to a poll!” poke
I might add, I think people are seriously overestimating the level of training of a typical medieval knight. Yes, many of them were no doubt highly trained in both armed and unarmed combat and kept themselves fit and war-ready. Many of them (I’d guess the majority, personally), though, were just better-armed bullies (especially the OP’s Teutons - I have a particularly low regard for that Order) , or gone to fat/drink, or suffered congenital problems, or focused a lot on mounted combat because that’s their wartime role was, or hell, just didn’t keep up the training because they were lazy.
crossbow. Try to make a COM shot and bleed him out. Use the bow itself as an unweildy club, if necessary. Chances are very good he’ll kill me anyway.