I did something like this in my last campaign. I had a variety of materials from which weapons and armor could be made. Most granted bonuses to damage or AC or just upped the hardness of the item. Then I had a list of 'upgrades' that a smith could select from when making the item. Different levels of sharpness that would increase the crit range or give bonuses to hit or damage at the cost of hardness (if it's really sharp it's also really easy to screw up the edge), special balances that would make the weapon hit harder, serrated blades to do wounding damage, etc. Each upgrade (and material type) increased the cost and the craft DC. For the equivalent of a +3 Keen longsword (in this case a Greensteel sword with clever balance and a honed edge) the DC might have been up around 45 (I don't really remember the numbers). The challenge then was to find a smith who could actually produce such a weapon, not to mention the money it would cost and a quantity of Greensteel, a metal found only in Gehenna and the Abyss.
I also had all non-standard weapons (including straight Mastework, +1 to hit) and armor bear a maker's mark somewhere. I don't think the players ever picked up on it but I used specific marks for items they found in various places (eg: all the weapons wielded by undead guards in an ancient crypt were made by the same smith... the former smith of the order that built the place).
Another idea to try out for size is having certain smiths be of such great skill that their artistry imbues properties into their craft whether they mean to do it or not. I imagine it would take a feat requiring a dozen or so ranks in Craft from a PC to do it, but such a smith might simply make +2 items every time he made anything. If he really focused and made his equivalent of a masterwork item it might come out as a Sunblade or something. Then if the PCs wanted to buy a Flaming Burst Greatsword they'd have to seek the legendary dwarven swordmaker Haupt Egrerin Dirrek of the Great Hall of the Western Range who works metal in a forge of elemental flame, imbuing them with such properties and the only living smith who can do it.
I really like the idea of items becoming magical spontaneously. I think I'm going to yoink that for the next game I run.
I also had all non-standard weapons (including straight Mastework, +1 to hit) and armor bear a maker's mark somewhere. I don't think the players ever picked up on it but I used specific marks for items they found in various places (eg: all the weapons wielded by undead guards in an ancient crypt were made by the same smith... the former smith of the order that built the place).
Another idea to try out for size is having certain smiths be of such great skill that their artistry imbues properties into their craft whether they mean to do it or not. I imagine it would take a feat requiring a dozen or so ranks in Craft from a PC to do it, but such a smith might simply make +2 items every time he made anything. If he really focused and made his equivalent of a masterwork item it might come out as a Sunblade or something. Then if the PCs wanted to buy a Flaming Burst Greatsword they'd have to seek the legendary dwarven swordmaker Haupt Egrerin Dirrek of the Great Hall of the Western Range who works metal in a forge of elemental flame, imbuing them with such properties and the only living smith who can do it.
I really like the idea of items becoming magical spontaneously. I think I'm going to yoink that for the next game I run.