Second Eye
This has been bothering me for the last hundred chapters or so. Witches are pretty much band-aids when it comes to technology. What if Anna dies? Doesn't have to be assassinated or anything, just old age is enough. That's it, no more cement, welding, or heavy metallurgy projects. Even if magical chineseman grabs the royal potty chair, rules over everyone and attracts witches like flies, there might not be a replacement found for decades - skills of witches are seemingly pulled out at random from a vast pool of abilities, we haven't seen a single repeating ability yet.