I am often at odds with myself as to how much magic there should be in the World of Fletnern. One of the things we did intentionally with Legend Quest was to make enchanting a weapon a secondary thing - When you want a magic sword, first you get a sword, then you get it enchanted. You don’t just go to a magic shop and buy a magic sword. What if the grip isn’t right? What if you wanted a certain kind of cross guard or pommel?
This makes enchanting a service you can buy in most major cities. It’s not cheap, but it is absolutely available. I know that goes against some GMs’ worlds, but to each his own, right? But how much magic do I allow in my world? Probably far more than most people would expect.
One of the consequences of making enchanting a service, is that it has a generally accepted price. Journeymen enchanters make about 300sc a day. That’s 30x what a carpenter makes, but still within the reach of some successful adventurers. But with an established cost, you can start doing some cost-benefit analysis. If you have to pay an enchanter four days (or ~1200sc) to enchant the sail on a ship in order to shave 10% off the travel time, then when is it worth it? Well, ironically (according to Grain Into Gold), the salary of a ship’s captain and crew is about 300sc per day. So if the sail will shave 10% of the travel, and therefore 10% of the payroll off the ship, then the sail only has to last 40 days in order to break even. If you could shave 10% of the payroll off a ship for six months with one magical sail, you would save yourself 4,200sc. (300sc per day x 10% x 180 days = 5400 - 1200 for the sail = 4200). Now, I’m not suggesting that a +10% speed sail only costs 1200sc (I don’t know, but I am writing myself a note to figure it out), but if it did ...
Which leads to the big question: So what? Any time an enchantment can last long enough to save a significant amount of time and therefore cost, then the people will be using magic to enhance their business. Solar glass is an alchemical that when used in greenhouses allows them to soak up sunlight, even on cloudy or rainy days. That means you can now grow tropical plants anywhere you want to. Is that worth a couple of thousand silver coins assuming it lasts 5-10 years? Yep!
OK - How do I justify magical weapons and armor? I actually ran through the math on this. Assume that you are actually paying a soldier during his training. Two years at 10sc p/ day, let’s just call it 8,000sc. Then add his equipment: spear, shield, chain mail. That is a pretty big investment. Assuming an officer has five years of experience, that investment is too much to risk. Now what keeps him alive best? The main combat enchantments in LQ are animated attack (increases your “to hit”), animated parry (decreases his “to hit”), and sharpness (decreases his armor protection, which effectively increases damage). Animated parry is easier and cheaper to cast than the others, and it therefore fairly dramatically reduces the enemy’s chance of scoring hits and thus lowers overall damage. My factory enchanters are not the greatest, but they can churn out a +20% parry shield for about 1,200sc. Risking 1,200 to protect ~18,000 - that’s a good bet. It is especially important if you know the history of the Latvich military and know that they got their keisters kicked at Rhum because the Rhoric snipers kept picking off their officers. Keeping those officers alive is a vital part of the new Latvich army.
So how much magic is there? There is as much magic as makes sense economically. For those cities that have enchantment factories, every officer will have some manner of magical item. Nearly every elven soldier has at least half a healing potion. Plantation owners make use of rain makers.
An extra point though: Golems can cost 12,000sc. Now a 12K golem is a fearsome fighting machine, but is it worth 25-30 mercenary soldiers (assuming it would last about a month in battle)? No. It just isn’t. So very few rulers have an army of golems hidden away. OK, a couple do, but these are the guys who have enchanters who are legitimately bored. The cost-benefit often shows that it is better/cheaper to just use more people.