You actually bring up a great point that is an issue that many newer players run into that could honestly use some polishing by the GM to make information presented a little more clear in pages.
Weapons that you may have deactivated in your Army pages for defensive and offensive aren't all of your weapons. Think of them as weapons sitting at your bases that are either ready to be deployed (active) or those that are still in storage (inactive).
In addition to that stockpile, you have your fully deployed military units, your divisions, air wings, etc that do the actual moving around and fighting in conflicts. Those are all considered active weapons but their weapons don't show up with your stockpile totals, so it can seem like your weapons are all in storage when in reality you have many roaming around your country in fully assembled units.
The game actually starts new players off with a military of full
The maintenance cost of the army should decline slightly with some reduction in the cost of ammunition.
the cost of maintaining the army can however fluctuate with the market price of some items that might be in short supply and increase in price.
if you want me to look into it, please let me know where it is.
world name, country name will help.