Shesulsa,
In traditional Hapkido, the dan bong takes three forms: (well, three lengths) - one that is 24 inches long, one that is 12 inches long (with or without rope) and one that is 4-5 inches long.
Dojunim Choi, Yong Sul used these weapons mainly in a striking capacity - the longest used in anti-sword, long knife defense, the two smaller as anti-personnel weapons. There was some limited joint locks, but they were fast and effecient, not like some of the 4 or 5 stage motions seen today.
The strikes were generally targeted against joints and soft spots (or nerve clusters) on the body. Striking was accomplished with both blunt end striking and wrist twisting motions. The second type of strike, using a twist of the wrist would not be very effective against large muscle groups, and produces most often only a sting there unless the strike is really on target - these strikes were generally targeted toward smaller bones or smaller joints, wrist, finger etc.
Having carried a 12 inch dan bong my entire career in nightclubs, I can say that for a simple weapon, it is very effective - moreover, I was never concerned it could be used against me if dropped - in the hands of most it is useless.