Dark Whisper Blade

The Dark Whisper Blade is rare dagger that is desired by magic-using classes like mages and warlocks and, to a lesser extent, druids and shaman.

Source
This dagger can sometimes be found in a Chest of Spoils, a reward for completing the quest Scepter of the Council and the repeatable quest Abyssal Scepters. Both quests are given by Bor Wildmane in Silithus.