One-handed weapons require only one hand, allowing for Off-hand Items and dual-wielding. However, note that weapons of differing melee and ranged types cannot be dual-wielded together.
All crossbows, slingshots, banjos, guitars, pistols, and accordions are ranged weapons. All other items are considered melee weapons unless otherwise noted.
The Disembodied Hand familiar can equip all one-handed weapons (with the exception of Chefstaves), regardless of level requirements, and convey the weapon's effects to you.