I'm thinking that they mostly reflect classical/ancient societies for most things. This is because few European/Western medieval societies had true empires. (the late Byzantines, true, but they collapsed, leaving mostly just the Ottomans). So mostly I want to preserve that feel.
On the other hand, steel makes things easier, so let's say steel is permitted. Bask and Tyleria and Parthann would almost certainly have steel, though you may want to restrict access to it depending on natural resources and trade availability. Many free cities and parts of Bregtoran and Silkur probably also have enough steel that it's not that unusual.
I don't see why we have to have paper. Something more like papyrus certainly. Probably vellum where papyrus isnt' as accessible.
Seige engines? eh, why not. We'll leave that up to writer discretion.
I think originally nothing later than very early rennaissance, meaning POSSIBLY some gun powder, but while it's not inconsistant with anything so far, I don't know that we should have even gunpowder. Tech should probably remain at Medieval levels. Plate armor, basic seige equipment, vellum, etc.
Social institutions aren't necessarily based on that, so social systems can be anything, and we can have universities and whatnot.
Sound good? clarifications? contentions?