A Drow Long Knife is an off-handed weapon first featured in the 3.5 edition Races of Eberron supplement and then in the 4th edition Eberron Player's Guide and is used by the drow of Xen'drik. This large knife is three-quarters the length of a longsword and has an outwardly curving hook on its end. Despite its length the blade is too slender to be classed as a short sword and is too large to be a dagger, so the weapon is classed as a long knife. These knives weigh 2lb, cost 15gp and are apart of the Heavy blade group in the 4th edition and a exotic light melee weapon in 3.5 edition.
Races of Eberron: Page 172
Eberron Player's Guide. David Noonan, Ari Marmell, and Robert J. Schwalb (2009). Wizards of the Coast. ISBN 0-7869-5100-1.Races of Eberron. Jesse Decker, Matthew Sernett, Gwendolyn F.M. Kestrel, & Keith Baker (2005). Wizards of the Coast. ISBN 0-7869-3658-4.