I explored the market price of graded wands and staves a couple weeks ago, and I’m pretty satisfied with that result.
Then I decided that granting graded items some limited spell casting ability — a few spells that can be used daily, sort of thing — could be pretty cool. The fire gauntlet of Allioch was implemented in part by making a lesser wand of military fire part of its construction, as a grade 5 quality.
Yesterday I got to thinking about the difference between spell trigger item market prices and ‘uses/day’ item market prices. A grade 8 wand (fourth-level, second-level, and two first-level spells; 8 charges) can cast its biggest spell twice per day. I’m confident in my reasoning behind the graded wand market price, but allowing the wand to be added to the gauntlet and used by a non-caster should probably move it to the ‘uses/day’ cost, something like that of an ‘eternal wand’ from late 3.x era… which should be somewhat more expensive, about twice as much.
Then it occurred to me that the ‘spell casting’ quality (that embeds the ‘wand’ into the other item) is a quality of a grade equal to the wand’s.
This means that the same grade 8 wand that costs 32,000 gp as a spell-trigger item is a grade 8 quality, not a collection of smaller qualities adding up to item grade 8.
A grade 8 quality can only be added to a grade 15 (or higher) item. That means that rather than a market price of 32,000 gp, the spell casting quality has a market price of 15*8*500= 60,000 gp, almost exactly double the market price of the original wand (and taking a huge bite out of the grades available to be assigned for this item… and not scaling with the grade of the item itself: it’s always a grade 8 wand).
Okay, adding a graded wand to a grade item as a ‘spell casting’ quality is not giving away too much. It might even be overcharging for what you get… but for now I’ll leave it. The ability for a sword to drop a wall of fire at need is not to be underestimated.
The level of detail and logical thought process you are applying to this matter is very impressive. I don’t know much about gaming, but I do admire all the work that goes into it.