Two-handed weapon

From NWNWiki

A two-handed weapon is a weapon whose weapon size is one category larger than its wielder. (That is, a large weapon for most player characters, and a medium weapon for gnomes and halflings.) These weapons require two hands to wield, so cannot be used in conjunction with a shield.

The advantage of using a two-handed weapon is having the strength modifier increased 50% before being added to damage inflicted by the weapon.