
Here is the basic idea:
Somewhere in Athkatla (or in another town/village) you would meet a wizard (Magnus Silverhand), who would make special items for you, but not in the same manner as Cromwell or Cespenar upgrade them.
He would enchant ONLY non-magical weapons or armors/shields for you, but you could decide the type of enchantment he puts on the item. There would be several sub-classes in the possible effects (enchantment bonus, equipped effects, combat abilities, general properties, etc.), and the player could choose from these lists the best combination for his/her new item. Each subclass would contain numerous possible effects, like +1,+2,+3.. enchantment levels, or different protection bonuses and attached spell bonuses in the Equipped effects sub-class. Every bonus to the weapon would have a price (the more powerful the effect is, the more gold would be required), and this cost would increase after every effect added to the item. An example:
-The PC has a non-magical normal Long Sword. He has the following options to choose from:
1. General Property bonuses
2. Equipped Effects
3. Combat Abilities
4. Enchantment Level
First, the PC picks the fourth option, the Enchantment Level. Magnus offers the following bonuses:
1. +1 (500 Gold)
2. +2 (2000 Gold)
3. +3 (5000 Gold)
4. +4 (9000 Gold)
There wouldn't be a +5 option, Magnus has no power to place such a powerful enchantment upon an item.
The PC picks Nr.2, +3 enchantment level bonus. He must pay 5000 Gold for this effect. Magnus asks him if he is satisfied with the current effects, or would choose more. The PC chooses "more". He decides to pick from the General Property bonuses sub-section:
1. Reduce weight to 1 (200 Gold)
2. Faster attack Speed by 1 (250 Gold)
3. Increase attack range by 1 (2500 Gold)
etc.
The PC's choice is to reduce the weight of his new sword to 1, so he picks the first option. It would cost him 200 Gold, but since this is a secondary effect already, there is a Gold penalty of 1000. This means he pays 1200 Gold for the second effect. Again, he decides to pick more (he has tons of Gold

1. Elemental damage weak/medium/heavy (1000/3000/6000 Gold)
2. Bonus poison damage weak/medium/heavy (750/3000/7000 Gold)
3. Stun effect, save vs. spell at 0,10%/hit short/medium/long (2000/5500/10000)
4. Bonus damage vs. cre type weak/medium/heavy (500/1500/4500 Gold)
5. Vorpal blade 20% chance to save vs. death at -2 or die (10000 Gold)
6. Dispel Magic on hit weak/medium/powerful (1250/4000/9000 Gold)
etc, you get the picture.
The PC decides to pick the Vorpal blade effect for 10000 Gold. But sionce this is a "third" effect on his weapon, there is a 5000 Gold penalty on the price, which means he pays 15000 Gold for this level of the enchanment.
He could continue forever (the penalty for the fourth enchantment would be 10000 Gold, 15000 for the fifth, etc.) if he would have enough money. But this time he is out of gold, so he decides to pay for the newly enchanted blade:
- it is a +3 Vorpal Long Sword, its weight is now 1, and it has 20% chance/hit to kill the opponent (save vs. death at -2). Its price is as follows:
+5000 for the enchantment level
+1200 for the weight bonus
+15000 for the vorpal effect
= 21200 Gold. Or something like that, the prices may change for balance

Any ideas?
TGM