Because Heroes have a habit of keeping secrets, after all.
It’s also very likely that the Heroes summoned in Faubley only used such convenient knowledge for themselves.
Which reminds me, the viewing crystals resemble digital cameras.
They might be a tool made by a past hero or their followers by combining modern knowledge with magic.
Come to think of it, do they use the parts that were in the carriage I requested?
Even I had the option of using that knowledge to attempt to improve my sales.
Well with the shield’s capabilities, using items or the slaves and monsters was more cost-effective so I didn’t, although I couldn’t really do it anyway because I don’t have the technical knowledge.