Heavy weapons
Heavy weapons, such as those made from gold or platinum,
are unwieldy but inflict additional damage. Without
the proper Exotic Weapon Proficiency feat (for
instance, heavy longsword), you suffer a –4 penalty on
attack rolls with a heavy weapon. Only weapons made entirely
or largely of metal (such as swords or axes) are affected;
other weapons (such as spears) are not.
A character can wield a heavy weapon one size category
smaller than his own in two hands to avoid the
attack penalty. For instance, a human swinging a light
mace made of gold with both hands, or an ogre wielding
a platinum longsword with two hands, does not suffer
the attack penalty.
You can never use the Weapon Finesse feat with a
weapon made of a heavy metal.
Weapons made of a heavy metal inflict increased
damage.
Old Damage (Each Die)/New Damage
1 - 1d2
1d2 - 1d3
1d3 - 1d4
1d4 - 1d6
1d6 - 1d8
1d8 or 1d10 - 2d6
1d12 - 2d8