Simple weapon

All characters except a druid, monk, or wizard is proficient with all simple weapons. In NWN2 a character cannot wield a weapon they do not have the proficiency for.

Some simple weapons are:

• Dagger
• Mace, heavy
• Mace, light
• Club
• Morningstar
• Spear
• Quarterstaff
• Dart
• Crossbow, light
• Crossbow, heavy
• Sling

See here for a full list.

D&D Comparison

In DnD 3.5 a character takes a -4 penalty to attack rolls when using a weapon she/he is not proficient with.