So with some actual free time again I've been digging into the Creation Kit deeper.
Figured out how to edit randomized lists of the items for sale by merchants. I'm thinking of making a big mod now to enhance the gameplay so I'll want to play characters longer.
I think my base philosophy is... it's too easy to get hold of powerful magic items and weapon/armor types through purchasing, smithing, and enchanting. Because of this, the item you get at the end of a quest or by killing a boss-level character are seldom worth using. Which means there is little reward for doing quests beyond just doing them to say you did them, or to advance a storyline (to another quest which likely also has a meaningless reward).
I want it so the best way to get the best gear is to go out and kill someone for it, or otherwise earn it. The stuff in shops or made with smithing will supplement and fill gaps, as will enchanting. But I want there to be that continual drive to go out and do quests to improve.
So I think I'm heading towards making it like this.
Magic weapons/armor/clothing/jewelry will be very rare to find in shops. Maybe around a 3% chance of them having a single such item. I might need to throw in a quest item or two for some of the rarer enchantment types, like Fortify Carry Weight, Banish, Absorb Health, etc, so it's still possible to get them. Potions unchanged.
Shopkeepers will have much fewer high quality weapons and armor. The majority of what you'll find for sale even at higher levels will be iron and steel. Maybe they'll have 2-3 pieces of higher quality weapons/armor, with Dwarven and Elven more common than Glass and Ebony even at high levels.
Do something to limit how easy it would be for a high level Smith to just crank out high quality armor/weapons. I'm thinking make it so it will be rare you can buy a high quality ingot... having instead to go mine them yourself. In addition, I can include some in the quest rewards and on boss and creature inventories, so completing quests and clearing dungeons helps give you materials to make and upgrade nicer items. Also imagine I can edit how many ingots/leather it takes to make an item so it requires more gathering.
Enchanting... oof. Need to figure out how to lessen the strength of the enchantment that you can make. If I could make it level dependent that would be good, so that you're able to make useful items, but the quest items you'll get would be more powerful than what you can make. So Enchanting becomes a way to fill gaps in your gear, but it's not the way to put together the best equipment set. At least not until really high levels.
Not sure yet how the Smithing and Enchanting work. I suspect strongly they are scripts... essentially little programs that are attached to the enchanting altar and forge/grinding wheel/workbench that run when you activate the object. Have done a tiny amount of script editing in the past, like making it so you could pick up a book without reading it by clicking on it, or could shift-click it if you wanted to read it. Probably going to have to learn a lot more for these kind of edits though.
It's going to be an ambitious project though. There's 100 merchant chests in the game. Each has a LeveledItem on it which is a list of what it can contain. Each of those pulls in items from other such sublists where I might be able to just edit all the sublists and it would touch all the merchants in the game, but knowing what all a change is affecting is going to require a lot of proofing. There's no reason those same lists can't be used to decide what to equip a bandit with, or to help determine a quest reward, so need to be careful I only affect the merchants.