As you’ve probably noticed, all weapons and accessories in Final Fantasy 13 are upgradeable. The process is fairly simple in that you just add components to the weapon or accessory of your choice, but there is a process to it, so if you just go around adding anything at any time, you’ll miss out on a LOT of experience.
The key to the whole thing is the multiplier. Adding certain types of components adds to your experience multiplier, while others take away from it.
There are two primary types of components in the game. There are organic types, and synthetic types. You can generally tell the type by its name. Bones, claws, hides, etc. are all organic types, while cabling, conductors and the like are all synthetic. If you sort them on the components screen you’ll see that the top is organic and the bottom is synthetic.
The organic types generally drop from beast type monsters. Begrimed claws, Bestial Claws, Wicked Fangs, these are all organic types and will add to your experience multiplier as you add them to your item, but they have low experience values.
The other type, the synthetic type, usually drops from mechanical enemies you fight. Insulated Cabling, Fiber-Optic Cables, and Superconductors are all synthetics and have high experience values but subtract from your experience multiplier.
If you haven’t figure it out already, your strategy is to first add organic components to get your multiplier up as high as you can (which maxes out at 3x, or 300% of the base experience value) and then add large numbers of synthetics to get a large experience boost, which will in turn drop the multiplier back down. The more synthetics you can add at once, the more benefit you’ll get before the multiplier drops back down.
In the beginning this will be fairly difficult, since you won’t have access to a lot of gil or components yet, but that’s ok.. you’ll more than make up for this later in the game.
A good strategy a little ways into the game will be selling some components to get better value out of other components. For example, the organic item Sturdy Bone gives a good amount of experience and bonus for the value, which allows you to sell other organic items that cost more and have less or equal experience for the value, and end up getting more bang for your buck in the process. This becomes very apparent later in the game when you run across components that you can sell for thousands of gil that don’t give you experience proportionate to the value of the item, so it only makes sense to sell it and buy other higher experience components from the proceeds.
There are a lot of numbers behind the scenes as well that change what experience value certain items get from certain components, but I don’t really have the space to provide that information here. Luckily though there is a really good upgrading guide on gamefaqs that has outlined all of this info, so I suggest you check it out. Not only does it go into great detail about the entire process, but it gives exact values that components give as well. It’s definitely a good read if you’re looking for specific values and want to get the most value out of your components as you play through the game.