AD&D 1E Three Things that can't be Fixed in 1e AD&D

[Celebrim]

There's two in-setting reasons why lots of magic weapons and armour might be made:

--- adventurers and-or nobility pay MUs or Artificers really well to make martial items to commission (this is where the high-end stuff comes from), or
--- nobility pay, or hire, or enslave, MUs or Artificers to mass-produce martial items to equip their guards, army officers, elite soldiers, and maybe even some of the line troops (this is where all the basic stuff comes from).

None of that makes the slightest bit of sense in the context of the rules.

1) You can't even make martial magical items until you are a 16th level M-U, so in a low magic setting there should be no magic swords (for example). The production rates for such items is lower than the rate they'd be destroyed to crushing blow, etc.
2) Every single magic item created of a permanent nature potentially costs 1 point of permanent Constitution loss. It's difficult to imagine any PC caster making such an item on commission, much less for the sort of peanuts that swords +1 are supposedly worth on the market. The smallest magic item should be priced at about 1/2 of a wish, a spell that incidentally ages you 5 years.
3) You have to be a 16th level M-U to manufacture this stuff and you need access to your spellbooks and laboratory. Good luck enslaving a M-U to mass produce these things. That's as dumb as trying to enslave Tony Stark to manufacture weapons for you.
4) The rules as written preclude any sort of mass production system. They require the harvesting of rare ingredients in usually short time frames and those ingredients cannot be sourced generally without DM aid.
5) Keep in mind that by the rules it is vastly easier and less risky to make a wand of magic missiles than a +1 sword and yet look at the market prices on the two items.

So sure, you can postulate that there exists some non-documented manner by which NPCs make these things not available to PCs, but that's my point.