Certainly, accidents can happen. However, the absolute majority of situations potentially dangerous in terms of injuries can be mitigated with competent actions by both the coach and the athlete. Keeping this in mind, our sport is far from being the most injury-prone compared to others where causing injury is often directly anticipated and encouraged by the rules.
It's someone who achieves maximum results with minimal effort. It doesn't matter how it looks: they may spend the entire training standing on the sidelines or race around like a maniac after the athlete. They may make decisions that seem bizarre from a layperson's point of view. The crucial thing is the result.
Not the number of hours spent on the ice. Not the ability to wrap the athlete in cotton wool. Not the degree of awe they inspire or the level of influence they wield. The result is all that matters.
The main quality of a good coach is understanding the process at the atomic level. Understanding precisely when to "tweak" something: where to apply pressure, where to release it, where to focus on performances, where to refine technique with corrections, where to fill the training with simple, massive repetitions, where to pause, and where to bring what's started to completion here and now.