[quote=HazmatMedic]
Ok, how about "pre-500 AD, but most melee weapons are allowed."?For example, the cinquedea mentioned above is allowed, but we can't say "but I COULD build a cannon because ..." as that would be too risky.
[/quote]

And what of things like some of the more sophisticated pole-arms? It really should be a flat "Pre-500 AD" else you leave the door open for shenanigans. I am also one to agree with SovereignGrave in lieu of the whole "Everyone is educated!" type of thing, since that kind of goes against one of your rules about mega-culture. If we keep to the time-frame, then for the most part large portions of societies will be rather uneducated, and actual academia would be highly limited at best.