One Hander

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

Fallout, Fallout 2
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.

Fallout Tactics
This trait increases your Small Guns, Unarmed and Throwing skill by 10% while lowering your Big Guns by 30%. There is no penalty for using two-handed weapons and no bonus for using one-handed weapons.

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.