I don't get it. What's up with sith names? When sith inquisitor becomes member of the dark council, he gets the name of Nox/Occulus/Imperius, yet the sith warrior does not, despite being dark lord of sith as well.
Darth Baras had his sith name despite being lord of sith, not darth, and he did not change his name after joining the Council or becoming the dark lord, yet Darth Thanaton had to become dark lord of sith to get his.
WHEN does sith get his 'special' name, after all?
My guess would be the Sith Warrior keeps his or her real name upon being bestowed the title of Darth. For example, Athleena Mawiven becomes Darth Athleena.
As for the SI, no idea why he or she is forced to adopt a regal name. As mentioned earlier, most Dark Lords of the Sith were given new names and they lived with it. And (IMO) the DS name happens to be the worst sounding of the bunch. Darth Imperius sounds cool, Darth Occulus sounds OK, Darth Nox sounds lame.