prologue
Don’t need to rehash the tempering complaints, but primarily my view is that bricking is good but the manuals themselves should be improved. However, I have a different suggestion that could help the system fit in better.
The motivation for this is the idea that current drops are fairly confined, so that every piece is like main stat & max life + 1 resist or occasional interesting thing, and that tempering is basically set up as an extension of the item drop rather than as a refinement step.
a bunch of relevant assertions you may or may not agree with
Items that dropped with 5 affixes would be much more exciting than the 3-affix drops we get, because they would be a richer system with far higher highs.
The primary argument against this is that it means a more complex task of digging through the items to figure out what is good.
Tempering is great because it simplifies the process of figuring out which drops are good.
Tempering is weakened by manuals that include incompatible affixes, leading to a lot of 0 or 100 outcomes from tempers.
Unlimited tempering would make it too easy to attach the perfect affix, but even if some other cost could be used to balance that, it would mean a lot of extra time spent sitting at the blacksmith, just as enchanting can currently mean a lot of time spent at the enchanter.
Summary
Add a color to each affix in a tempering manual, which corresponds to a rarity level for that affix. Then allow items to drop with colored tempering slots, which enable you to pick the affix with the same color when you temper, or to roll as normal. So a white slot could guarantee a white temper from whatever manual, an orange slot an orange temper, etc.
Additional comments
Could be white/blue/yellow/orange/gold or some other scheme to keep it distinct.
The colors should correspond to a fixed, known temper rate when you roll normally.
So now, the temper that you get is much more a property of the item itself, which you are revealing, instead of a random chance you’re hoping for, but you also don’t have to dig through 5 separate affixes when you are choosing what to keep.