You could make the quality of the weapon dependant on the type of weapon or enchantment (ie. swordsmanship = better sword, illusion = better enchantment). You can be a little creative for the skill used for each construction. It could also be a percentage chance that the craft or enchantment succeeds.
Having a special place to do it would probably be the best way to go. Like have an forge for weapon crafting where smiths provide you with equipment for a limited time (for a price of course
) and the same with mages that assist you in writing runes on the weapon, or something to that effect.Anyway, I'm kind of thinking out loud here, let me know what you think
