There were plenty of blacksmith shops in Chang'an City, but most of them mainly produced farming tools like sickles, hoes, and grass forks, or everyday tools like kitchen knives and axes.
Although players could learn the blacksmith side profession from these shops, the blueprints they could obtain were quite basic and couldn't forge proper weapons.
—Unless the player was willing to use kitchen knives, sickles, or grass forks as weapons.
Despite the grass fork being pretty strong and particularly effective against a certain female sorcerer pile driver, there probably weren't many players willing to use it as their primary weapon...probably.
If one wanted to learn how to forge proper swords or commission the forging of proper swords, they would have to find a high-level blacksmith.
However, there weren't many of these blacksmiths.
The more troublesome thing was that there were no obvious signs on these shops from the outside, so players had to go in and ask for themselves.