Size category modifiers?

[Bioboygamer]

A friend created a build that uses a combination of weapon materials, spells, and traits that can do enormous amounts of damage via hitting with the equivalent of a Colossal-sized weapon. One of the traits that allows this is the variant Tiefling ability 16:

"You have over-sized limbs, allowing you to use Large weapons without penalty."

My friend argues that, for a Large-sized tiefling, the ability would allow them to use weapons the next size category up.

Is this how it would work, or are my friend's dreams of 3d8 weapon damage with 30 ft. reach fated to disappear?

[Avoron]

RAI, quite possibly. RAW, no.

Also, remember that reach is not dependent on weapon size; rather, it depends on the size of the wielder.

And if you want great base weapon damage, natural weapons are the way to go.