D&D 4E Economy of Inherent Bonuses

[Balesir]

It occurs to me that the discovery and ensuing battle over residuum could be a pretty great campaign hook at some point in the future, if I decide I'm ready to start using items more liberally again!

Yep - one of the things that occurred to me as I contemplated the "residuum separate and non-creatable" rules I mentioned is that the "residuum mines" (whatever form they take) would form a pretty amazing plot hook/political hotspot!

I'm thinking something along the lines of "there are only magic weapons that weren't forged by normal people", i.e. naturally occurring magic stone, blessed weapons, cursed weapons, extraplanar items, artifacts, etc. Ideally, each magic item they encounter would be interesting in its own way - interesting enough to have a story hook of some kind, should the characters choose to investigate it.

If you want no residuum, I would call everything artifacts, personally - they don't have to have all the Concordance stuff associated with them, as demonstrated in the Mordenkainen's Magical Emporium book, which has a hammer and a shield (IIRC) that are simple artifacts.

If you don't do this, it would imply that a "disenchant" ritual can be researched that will render the items that there are into residuum, which could then be made into other items. This would then amount to a "limited residuum" campaign (which I personally would prefer, because it gives a bit more customising power into the players' hands, but it sounds like you are after something different).

Edit to add: it occurs to me that, if you did have a few magic items but mostly artifacts, there might be a potential campaign development whereby the PCs research Disenchant and Enchant Item rituals, thus discovering that they can change the current form of this stuff called "residuum" (or "orichalcum", or whatever) as a prelude to them discovering that a source of "mined" (or grown, or harvested from dead magical beasts, or whatever) orichalcum has been found by those ignorant of how to use it...