Well, I found the issue. Win10 had an update yesterday and in the process it reported file corruptions. An hour-long SDD check and repair. And Archer is working fine.
No idea specifically what was corrupted, but it seems my C drive is having issues.

Weird behavior with monster light / dark radius
 

On a new char I started I noticed some unexpected behavior that (probably?) seems like a bug. In the 'Trouble at Home' quest, I attacked a mean mercenary with a ranged attack. Upon waking up, he suddenly had a range 1 light radius. I didn't think this was unusual until I later attacked a silver jelly (I think?), which put a range 1 darkness radius around it only after I had woken it up. Shouldn't at least the jelly always have the dark radius? It could make some sense that the mercs don't light their torch until they wake up, but it is pretty weird to use a ranged attack on a jelly only for it to put up a shield of darkness so you have to move in closer to target it.

Who knows, I could have sworn that previously things like dreadmasters / lords always had their radius even while asleep.

I don't think I've changed anything there lately, will note it and review whether the light/darkness should be active on sleeping monsters.

That behavior has been around on the sleeping Mercenaries and Silver jellies for so long it seems natural to me. The same appears in the Theros Cleaning the Lab.

I have a quick question about item generation. Outside of vaults, is it just very unlikely to find a very out of depth item? Or is it literally impossible? I play coffee-break mode if that makes a difference.

My memory may be faulty, but I feel like in Vanilla, if you played enough hours, you would very (very very) occasionally run into an extreme OOD item, and I get the feeling in Frog this just doesn't happen at all. For example I could have sworn there were times I found one of the later dungeon spellbooks very early. Meanwhile in Frog, I don't think I've ever once had a character find their 4th spellbook, and I've taken a decent # of characters to CL40+, DL60-75 (though never beyond that). But maybe I'm wrong about Vanilla and that's just my memory of Nethack bleeding over, where you could in theory find a wand of wishing on DL1.

I do like to have that feeling that, no matter how ridiculously unlikely, it is theoretically possible to find Boots of Feanor on DL1. The closest I've gotten was getting the One Ring from Smeagol, but I know that's hard coded.

I believe in Frog you can get level-boosted normal items, and (very rarely) extremely level-boosted artifacts and egos, but you can't get extremely level-boosted normal items. So you could (probably?) roll Feanor at DL1 in theory, it's just super-hyper-unlikely, but you can never a find a power dragon scale mail or a potion of experience at DL1.

Extremely out-of-depth items are fairly common in V.

Another quick question - I hate creating separate threads for what is (hopefully) a simple question, hope that's okay.

Is there any resource, either in-game or on the web, explaining Samurai Stance, Form, Posture or Guard Position (which I think are all terms for the same thing and Kata as well).

I'm looking at the source samurai.c and it looks like Koukijin adds +5 to all stats but also adds elemental vulnerabilities. Musou looks like it adds all kinds of intrinsics.

My current CL 26 Samurai only has one option available, Iai, and I have no idea what it does.

Samurai (and Monk) postures are caught in a trap where people don't use them much because they're poorly documented (and the classes are so strong anyway there's little need to complicate play); and because they are so easy to not-use there aren't very many calls to document them better. I do still know I should document them better at some point :)

As far as I can tell from looking at the code:
- Iai: gives a single retaliatory blow (with a +20 to-hit bonus) against monster melee attacks, but any damage you suffer (from any source) is increased by 20%. Any melee attacks from you (including the retaliatory blow) dispel this posture
- Huujin/Fuujin: gives reflection unless blind, at the cost of -1.00 to blows
- Koukijin: gives +5 to all stats and +50 melee to-hit, at the cost of -50 AC, vulnerability to the four base elements and no regen. Using inventory items tends to dispel this posture
- Musou: gives full telepathy and ultimate resistance, halves most types of damage, and gives a full round of retaliatory blows against monster melee attacks; but practically any action other than retaliation dispels this posture

Back a few years ago under PosCheng(?) someone posted an analysis of all the effects, most of which seemed to have larger penalties than benefits. As I, vaguely, recall, all but one of the Monk's were deemed suicidal.

Sadly I didn't save it, but I did save the Human powers breakdown.

That would be mighty helpful to have in-game. I find weird that some skills and spells lack descriptions at all, and would be really thankful if most of the descriptions that are in would just spill the beans already. I detest making non-informed decisions in a perma-death game.

So, as a new player, I have a few questions that I would like to ask that I didn't get answers for in the Discord channel. There are experienced and helpful players there, but the bulk of the developers and code divers seem to be here.

1 - Whenever I see a class that have a Riding skill cap above Beginner (I see either Skilled and above or 0), I kinda feel like it is a big missed opportunity for the character to not make use of it. I found out that some classes that, despite having good Riding caps, don't really make good use of it (Samurai can't Concentrate on the saddle, Daggermasters can't dual wield properly). I don't even have to go too much out of my way to find Riding weapons most of the time, and the only thing that I really feel like I'm giving up is on ranged combat. Is there any article or essay regarding riding, so I can learn more about it? I know it is a play-style among many others, but is it even particularly good to just stand on foot, double handing a weapon or dual wielding or having a shield?

2 - I managed to find some documentation regarding various aspects of the game as the _info.txt files. Neat and all but for the most part it is information I can find in-game in a more readable format. What I actually want to find is documentation about classes, specially monster classes. Is there anything like that among these files, or I need to seach the internet?

3 - While on the subject of monsters, I kinda feel enamored for the Orc Fighter because I have an obsession of playing with underdogs. If Kobolds or Skaven were an option, that would be them, but as they aren't, making a lowly Snaga a Warlord is a goal that really entices me. Specially as they can evolve, unlike a standard-mode Snotling or Kobold. Have people written anything regarding Orc Fighters? A guide, or at least impressions that could be enlightening? As well the best way to make use of the only racial power they have, summoning orcs.

4 - Artifacts. Let us say I got a low value artifact weapon and want to convert to another weapon chassis (non-riding into riding, is what I did the most so far). I understand that non-ego targets are a necessity, but how about enchantments? If I want to turn a Glaive into an artifact, it would be better to be a plain Glaive or the best Glaive +X +Y I can get?

For now it is that. I got over the basics for the most part by playing obsessively (got Angband vanilla a week or two ago, three days later found FCB, it is the only thing I play now) and asking on Discord. These are the only questions I have that come to mind right now.