Don't get me wrong i love the idea of having an ample selection of weapon types to choose from but the trick here is making it with a degree of sophistication without it being overwhelmingly complicated.
First you have to choose whether the weapons tech tree be based on quality of materials:
Research Crude Iron Weapons, Improved Iron Weapons, and ect, ect
Or base it on Weapon type and have materials researched elsewhere:
Primitive Spears --> Crude Spears --> Improved Spears --> Advanced Spears --> Superior Spears --> Ect, Ect
|--> Primitive Javelins --> Ect, Ect |--> Crude Pikes-->Ect, Ect
The idea, in theory, is simple. All spear, or more accurately pole weapons, are based into one section which in turn makes it easier for the player to decide how they want to define their armies. And by having Materials like iron be part of a different tech branch can also help, us, the players to costumize our researched weapons with specific qualities. Say, you have access to shortswords but have only researched copper smelting. The problem in a traditional method would be that your shortswords are useless if you need to research iron smelting in order to properly use the shortsword tech. But what i'm suggesting is instead if you have access to shortswords then you can design the blade's hilt, pommel, guard and blade followed with materials used (copper, bronze, iron, steel, ect, ect).
Another beauty about keeping the materials as a seperate tech is that it can allow us, the players, to be creative in making base alloys to be used as materials in turn. Say, you have access to mithral (known for light weight), Adamantium (legendary for its strength) silver (a natural anti-magical creature metal) and...dark iron (for magic resistance) and then were allowed to combine these metals into an alloy.... , well lets just say you could make more exotic and effortive base materials for arms and armor than the original key ingredients would be.
Also i believe the levels of a weapon tech (Crude, Improved, Advanced) should effect not the amount of damage but rather the overall cost to produce that particular weapon. This would include: the rate at which a weapon can be produced, the amount of materials to produce it and the price tag to make it. This would help keep armies small at first and as time progresses they would get bigger as the weapons become cheaper to make.