An extensive discussion of the name Hwa Rang is given in an excellent article: "Notes on the Historical Development of Korean Martial Arts - An Addendum to Young's History and Development of Tae Kyon", by Willy Pieters, the Journal of Asian Martial Arts (JAMA), Vol 3, number 1, 83-89(1994).
Robert Young's article (also well worth reading) is in JAMA, Vol 2, number 2, 45-69.
The literal translation of Hwa Rang is not very useful in finding meaning of the Historical group the Hwa Rang. The 'Hwa' may have been merely a salutation (like 'good sir'), but also refers to growth or development or flowering, or just about anything the opposite of diminishing. The Rang term is too diverse to pin down, but has some sense of banding together. The 'hwaju' were group leaders, and the 'nangdo' were the followers (in the Hwa Rang groups). They were youth of the aristocracy.
The Hwa Rang have also been called Kukson and sollang. Indeed, the terms hwa rang may refer to a shaman, and has even been the name of a brand of cigarettes! [There are Japanese cigarette brands of "Hope" and "Peace"].
It has been recorded that the Hwa Rang were called on to fight in times of strife (and they fought well), but there is no evidence that they were a separate force. There is evidence of training in weapons, but no specific bare hands arts are recorded. Most probably, the original martial arts (court arts - kuk sul, village arts - sado, kicking based arts - Tae Kyon, fist based arts - Soo Baek, and Shaolin derivatives) which had a place in the general population were the basis for their fighting (if they dropped their sword).
Tom Osborn.