- Rules Compendium, page 270 Off-Hand: An off-hand weapon is light enough that you can hold it and attack effectively with it while holding a weapon in your main hand. You can’t attack with both weapons in the same turn, unless you have a power that lets you do so, but you can attack with either weapon.
- Rules Compendium, page 245 Draw or Sheathe a Weapon Minor Action
- Rules Compendium, page 245 Drop a Held Item Free Action
- Rules Compendium, page 270 Load: Any weapon that has the load property requires two hands to load, even if only one hand is used to attack with it.
D&D allows an adventurer to carry two weapons simultaneously. Some adventurers have a power that allows them to use both weapons in the same turn, or a feat that provides extra defense or damage with two weapons, however most adventurers are limited to only using one weapon in a turn.
The Players handbook specifically indicates which weapons are off-hand capable. These weapons are light weapons that are easy to wield in a weaker hand, and still do damage with the off-hand. Any weapon not listed as an off-hand weapon is simply unusable in the off-hand. It can still be carried in the off-hand, just not used for attack or defense (unless a power or feat says otherwise).
If an adventurer is holding two weapons, and one of them is ranged, we assume that the ranged weapon is loaded with standard ammunition at the start of an encounter unless the adventurer declares otherwise prior to rolling initiative, however after that one round has been fired, the adventurer will have to either sheathe or drop the non-ranged weapon before reloading the ranged weapon. For example, a thief holding a sling in the main hand and a short sword in the off hand would have to sheathe the short sword as a minor action before loading the sling as a free action.
Exchanging weapons (or any items) between two hands is a minor action unless a feat or power makes it a free action.