The difference between a Dagger and a Dirk is largely in the personal understanding. The Dirk has it's origins as a Naval weapon, sort of a small sword/large dagger piece. Through my study of swords and accompanying side arms, a Dirk is usually 12 to 22 inches in overall length, whereas a dagger is typically 2 to 10 inches.

There are those, however, who will disagree with me...and so I let them.

Spec's:
Blade Style: Double edge dagger
Blade Type: 440 stainless steel
Blade Length: 7"
Handle: Pakka wood handle; Brass hilt; Brass Bone Crusher pommel
Overall length: 12"