Weapon Experience

Weapon EXP is different from normal EXP in that it goes towards increasing a character's Weapon Rank, allowing them to use more powerful weapons. Staves have especially high ranks in this area, but most weapons are only 1 or 2 in this particular stat. The general rule that the harder a weapon is to use (based on things such as Hit%), the higher Weapon EXP it will have.

It is unknown why SS-ranked weapons have points in this category, as that is the highest rank obtainable and it no longer matters.

Myths
Some people say Forging heavier weapons in Path of radiance/Radiant dawn will get you more Wexp this is untrue