Were you looking for the dagger called the [Searing Sunblade]?

The Sunblade are group of blood elves loyal to Kael'thas Sunstrider who guard the Magisters' Terrace and the Sunwell Plateau on the Isle of Quel'Danas from interlopers.

They are the elite counterparts to the Dawnblade blood elves that oversee the rest of the island and serve as the front lines against the Scourge, the Shattered Sun Offensive, and even the wretched.

Their armies in Sunwell Plateau are incredibly dangerous and even just one protector was able to gruesomely murder half the SSO army near the entrance. The rest of the sinister Sunblade armies guard the way from the plaza into the Dead Scar, where their Felblood successors lurk beyond.