Martial Weapon Proficiency

This feat negates the -4 penalty from using a martial weapon untrained. You may take this feat once for each martial weapon you wish to be proficient with.

Contrary to some rumors, you cannot take one feat to learn all martial weapons at once. The PnP D20 rules are exactly the same in this regard. This can be immediately verified by creating a new Wizard character and selecting a feat like "Martial Weapon Proficiency- Greatsword" or "Martial Weapon Proficiency- Battleaxe". However, taking one level of Fighter, Barbarian, Paladin, or Ranger will give you proficiency in all martial weapons.