"The Sword and Dagger", or "the Sword and Dagger of the Jhereg", were a team of two highly skilled female assassins at the time of Yendi. Quite unusually, one of them was an Easterner; Cawti, "the Dagger of the Jhereg". Her partner, "the Sword of the Jhereg", was Norathar. The nicknames are probably in reference to their individual weapons of preference, although their respective heights might have also been an influence.
Their fees were commensurate with their reputation and skill; generally starting at about three times the going rate, and scaling up rapidly from there.
The Sword and Dagger ended their work as assassins after killing Vlad Taltos, and being killed themselves. Although all the parties involved were revivified, it was subsequently discovered that Norathar was the legitimate Dragon Heir, marking an end to her association with the Jhereg. (This discovery helped in the unraveling of a Yendi Conspiracy which had led to her previous disgrace.)
Cawti, on the other hand continued on as a part-time assassin, even after marrying Vlad, but eventually gave this up when she became involved with Kelly's Movement.