Here's how I see it. The native arachnids are really fierce, they've repelled most settlement over the last several hundred years, and the planet's lack of obvious wealth ensures that no concerted effort is made to conquer it.
There's two hundred thousand settlers, at tech level two. Tech two is Renaissance level tech. Incidentally, the "bicorne" was a hat typically worn by soldiers of that era in Earth history. It is best known as the hat worn by Revolutionary War soldiers in America. So I gather from this that there is some sort of fixation with that point in Earth history. For whatever reason, there is little interest in the more powerful vehicles and weapons of the Imperium.
Being that they're under constant attack from the critters, this is significant. More than likely, the local religion has something to do with it. Or perhaps they are ruled by a warrior culture that just doesn't think that plastercating the hordes of critters with a VRFGG isn't very sporting. Maybe they place a lot of value in defeating the creatures in hand-to-hand combat.
The world isn't actually amber zoned, so I don't think the settlers actually resist contact with Travellers, they just limit trade to lower tech stuff that doesn't go against their culture, in exchange for simple things like food and water. Maybe they'll even accept new settlers who give up all their tech and beat down an arachnid hand to claw.
I tend to use original Earthian culture like it is in Futurama. It's the year 56XX, people just assume that George Washington slew the Russians with his fabled .50 slug-throwers, while working the mean streets of LA ("The question you have to ask yourself is, do you feel lucky, comrade?") Leads to some hilarious gaffes.
However, I love the "warrior culture" reasoning. Sticking with much of my original thought, the human natives must have adapted their culture to survive on this dangerous world, and forming quasi-religious "battle brotherhoods" that have specific requirements as to what weapons they may use and tactics they may take would fit right in.
The tricorne came first (1600's - 1700's), then the bicorne (very late 18th c. - early 19th c.), then the shako (early 1800's).
Alas!!! I stand corrected! Well now we have more Napoleonic dudes running around.
Maybe we'll finally get some use outta the Napoleonic minis floating around the hobby shop I frequent. I swear those miniatures are thirty years old, still neatly bagged, hanging from peg-board hooks and waiting to be purchased. I like gaming with grognards.
The Bicornnians, named so for the distintive hats the natives wear
I'm ripping off Jack Freaking Vance, you better believe I am going to use distinctive (odd) headgear! Thanks!
Living around the drying oceans of their world in small independant City States, in which the upper classes think to live an idyllic lifestyle. The main source of revenue is the mining of Potassium Nitrate, which is mined from layers of strata from the remains of extinct ancient fauna of the world's more verdant phase. In their battles with a native species, the Krvn, it is considered more manly to use sword and pike, though they do use some of their profits from selling the potassium nitrate (mostly used as fertilizer on Glisten, Ffudn, Tirem and other worlds involved in hydroponic farming) to buy simple higher tech equipment such as rifles or mining equipment. The Krvn also use the potassium nitrate as fertilizer in their caves to grow fungus, one might think this may be reason for the fierce conflict. However, the Bicornnians are somewhat reticent and standoffish to outsiders, and offworders have rarely seen the mining sites. This hides a deep dark secret, the Bicornnians, have been using the Krvn as slaves. The only way this has been possible without the Imperial authorities moving in, is the upper classes convincing the authorities that the Krvn are little more than animals. However, there is a growing movement amongst regular Bicornnians that this is wrong, that the Krvn are sentinent and should be treated as such. Many state that the Krvn, freed, would still work in the mines, in mutual benefit to both peoples. The Lords of Bicornn fiercely disagree and blame outside corporate interests of interfering with their world's ancient ways...
I love it, but I think I'm going to modify this somewhat.
My new conception is that there is one group of native aliens and two groups of humans resident on the planet.
The native "aliens" are the Krvn. They have a society with extreme biological stratification. The males are the warriors and the females are the Matrons of each colony (I might keep the name Tumble, it has a good ring to it). Due to the extremely limited space (it's a tiny world) the Tumbles are engaged in constant ritualized warfare. The Krvn are semi-sentient in the way that they have no real identity as individuals; instead, each warrior or Matron identifies so strongly with their home Tumble that they have almost no individuality. The constant warfare has become highly structured, and is devoted to acquiring the battle standards of opposing forces.
In this conception,perhaps the nucleus of each colony is actually something non-organic, like the radioactive piles used by the ghosts in another Vance story
The King of Thieves (which can also be found by following the Vance link in my first post). If so, this source of radioactive ores would be a hidden source of revenue if it is ever discovered, albeit to the destruction of the native life.
The first human group are the remnants of a colony ship that crashed here shortly before the Long Night. The passengers regressed, due in part to a lack of metal ores, and partly because of the extreme savagery of the native fauna, including the Krvn. They adapted and also engage in ritualized battle with the natives, although their inclusion probably required the inclusion of a new set of Codes of Combat. They call their strongholds Tumbles as well, and otherwise fit in. I have already established Venom Brandy (brewed with the venom of Krvn added) as a local export, so this fits. Their battle brotherhoods (see above) restrict them to specific (Renaissance tech) weapons and tactics, which neatly explains their given TL without problem.
The second human group is a set of capitalists who have created a betting lodge on the planet. They have the highest tech level on the planet, and make their money from tourists betting on the local battles. This also allows me to add morally-bankrupt corporate chicanery without using one of the more established megacorporations (I get bored with them after a while).