D&D4 Wiki
Attack bonus if proficient +3
Weapon die ([W]) 1d4
Type melee
Range 5/10
Handedness one-handed
Proficiency category simple
Weapon group
Weapon properties off-hand, light thrown
Price 1 gp
Weight 1 lb.

A dagger is a simple one-handed melee weapon in the light blade weapon group.[PH:218]

A dagger is an off-hand weapon. A character can use a dagger to make attacks even while holding another one-handed weapon in the other hand, and can use the other one-handed weapon to make attacks even if it isn't an off-hand weapon. A dagger is also a light thrown weapon, so a character can throw it as a ranged attack.

All classes have weapon proficiency with the dagger as a class trait. Swordmages have implement proficiency with light blades, including the dagger. Monks and sorcerers also have implement proficiency with the dagger.