Here a Guide i saw on how to upgrade weapons to MAX efficiently.
This will be a guide on the best ways to fully upgrade your weapons.
Not recommended until later in the game, specifically chapter 11 onwards.
The first rule is that each component for upgrading has a hidden multiplier value.
Generally organic raise the multiplier but give a low EXP yield, and mechanical items have a large EXP boost and reduce the multiplier.
You can increase the multiplier easily with Sturdy Bone, Barbed Tail and Vibrant Ooze, all available to buy for 80 gil. With 36 of either of these items you will instantly increase the EXP multiplier to x3 on you item.
The next step is to use a large amount of a mechanical component in one go to maximize the effect of the x3 multiplier you have achieved.
As a general rule of thumb, each weapon has three stages and to increase an initial weapon from Lv. 1 to max costs 50,000EXP, intermediate from Lv.1 to max costs 450,000EXP, and finally ultimate weapons require approximately 1,500,000EXP.
The best EXP giving components are: (all EXP boosts are averages)
Ultracompact Reactor - EXP 40,000, Buy Price 50,000
Particle Accelerator - EXP 4,800, Buy Price 10,000
Tesla Turbine - EXP 823, Buy Price 1,800
Super Charger - EXP 774, Buy Price 1,600
Turboprop - EXP 768, Buy Price 1,600
So following these rules you can quickly, and using your gil most effectively, fully upgrade each weapon.
So as a summary:
1, Choose equipment to upgrade.
2, Use 36 Sturdy Bones, Barbed Tails or Vibrant ooze to get a x3 bonus.
3, Use correct amount of a single EXP boosting component to instantly bring it to its maximum level.
4, If possible use transformational catalyst required to transform item into its superior form.
5, Return to step 2 and repeat until your weapon is fully upgraded.
