Killing is simple.
One just has to find the right moment to strike a fatal point on a person or beast. Most go for the neck, others target the heart, and the most powerful ones aim for the head.
Either way, the endgame is to end the battle with your life intact while the opponent is not. At the right moment, that can be achieved.
However, in moments when one has to subdue the target, it becomes a completely different matter. This time, instead of going for the kill, one has to start thinking of ways to remain alive while finding ways to knock out their target.
And if the target is a Level 4 Tier 12 beast, then the situation becomes dire.
Klaus's uncles found themselves in this situation.
Their target is dangerous.
Of course, they managed to win the first round, injuring it, exhausting it, and wearing down its stamina. However, it is still a dangerous target.