With every action, there is a proper and correct technique to do it safely. This applies to every action from throwing a baseball, shot put, discus, to swinging a bat or manipulating melee weapons.
The danger lies in failure to do the technique properly. This is why each of these activities are typically taught by an instructor and with little or no load. The consequences of swinging a 5 lb bat with bad form is going to be much less than the consequence of swinging a 95lb weight with bad form.
Proper form in each of these typically keeps the thoracic portion of the torso rigid, or in the correct orientation so that the load is absorbed top to bottom as opposed from side to side.
The number one danger of swinging weights in any form is the shearing forces that pull on the spinal column.
Keep in mind that kettlebell routines are designed around swinging a weight. The key is proper technique. That is why the "cheat reps" are not recommended for beginners. It takes time to strengthen the core to what it needs to do those reps, as well as develop the technique to do it safely.