Exotic Weapon Proficiency (Thorium Weapons)

Appropriate proficiency with the non-thorium version of the weapon

You are proficient with a particular weapon made out of thorium and may add half your Strength bonus to damage rolls. Thus, an attack with a one-handed thorium weapon adds 1.5× your Strength bonus, while an attack with a two-handed thorium weapon adds double your Strength bonus.

Characters who are not proficient with thorium weapons suffer a −4 penalty on attack rolls with them, even if they are proficient with a non-thorium version of the weapon. Characters receive their normal Strength bonus to damage rolls.

You can use weapons made out of thorium effectively.