12 Weapon Proficiency
Being proficient in a weapon means you can add your Attack Bonus to attack rolls made with that weapon. If you're not proficient, you can still use the weapon but cannot add your Attack Bonus.
Fighters, Rangers and Paladins start with 4 weapon proficiencies and gain 1 weapon proficiency every other level after 1st. (1 at 3rd, 1 at 5th, 1 at 7th, etc.)
Only true Fighters can also Specialize in a weapon.
Clerics start with 3 weapon proficiencies and gain 1 weapon proficiency per every 3 levels.
(1 at 4th, 1 at 7th, etc.)
Clerics may wear any armor and have no weapon restrictions.
Druids start with 3 weapon proficiencies and gain 1 weapon proficiency per every 4 levels.
(1 at 5th, 1 at 9th, etc.)
Druids may not utilize metal armor of any type, and they are likewise limited to wooden shields. Druids may utilize any one-handed melee weapons, as well as staff, sling, and short bow.
Thieves and assassins start with 3 weapon proficiencies and gain 1 weapon proficiency per every 3 levels. (1 at 4th, 1 at 7th, etc.)
Thieves may wear leather armor without penalty to thieving abilities and have no weapon restrictions.
The Assassins' Assassinate attack must be carried out with a one-handed piercing weapon, such as a dagger or sword.
Magic Users start with 2 weapon proficiencies and gain no new proficiencies as they spend most of their training time studying books and not practicing with weapons.