One Hander

One Hander (called Unidextrous in TORN) is a Fallout, Fallout 2, Fallout Tactics, Van Buren, Lionheart and TORN trait.

Fallout, Fallout 2, Fallout Tactics
This trait gives a -40% chance to hit with two-handed weapons, but +20% to hit with weapons that only require one hand.

Affected weapons are Unarmed, Melee, Small Guns and Energy Weapons pistols, and Throwing weapons.

Completely unarmed attacks, such as Hammer Punch, are unaffected by this trait giving them neither a bonus nor penalty.

J.E. Sawyer's Fallout RPG
This trait provides a +2 chance to hit with one-handed weapons, but -2 to hit with two-handed weapons.

Lionheart
You suffer an initial -10 to Two-Handed Weapon skill and -10 to Ranged Weapon skill but obtain a +10 to One-Handed Weapon Skill.

TORN
The character is +20% to-hit with one-handed weapons, but -40% to-hit with two-handed weapons and suffers an additional -40% to-hit penalty when dual-wielding.