[HoneyBadger]

Endoperez, I very much agree that I'd like to see different magic items at different ages (For that matter, I'd like to see 2-4 more ages). Forge wouldn't represent massive technical achievements, it would simply represent different styles of armor or weapons differentiating one unit from another. More resources could be put into creating more elite units who can afford the best armor and fine weapons, and more gold could be put into equipping elite soldiers. Having a Forge for some nations like Ermor for instance might mean more, but not absolutely. for every nation. Jotuns with a Forge might invent the sling but jotuns without one may be stuck with spears, javelins, and boulders. It wouldn't mean Jotuns would invent gunpowder-although maybe late era Tien'Chi does in the form of crude fireworks with limited battlefield value. My concept of the Forge is as a stepping stone to differentiate a province with a much higher technological infrastructure than others, a situation which historically often enough did occur, and which wouldn't be out of place. If you wanted the best steel, you went to Toledo or Damaskus. Venice had glassblowers and the Dutch had skilled craftspeople. Constantinople had silk and the weight of a thousand years of relative enlightenment. Other places were at best, well...midieval. You can compare this with places like Delphi and Jerusalem as far as temples go. As far as labs go, it's harder to draw a real-world comparison, but for ritual spells certainly Stonehenge comes to mind.
If you want to build the best armies then you need an infrastructure. A big part of the reason Rome was so successful is because it had Greece. Greek artizans, thinkers, and artists, and Greek soldiers who were both tough and smart. If Rome had been founded in England, we probably wouldn't be speaking English right now.