Threatening another person with violence can include:
However, it is not always the case that the threat can be proved by police beyond reasonable doubt.
At first it may appear that these are difficult charges to defend as it is easy to be reckless in making a threat. If you think about environments where passions run hot such as football games, or even out socialising with friends and have had a few too many drinks.
However the circumstances and the nature of the relationship between the victim and accused person is important. If a relationship between two persons is dysfunctional and words such as "do that again and I'll kill you" becomes between the two people, then the threat is not a threat that would attract a criminal penalty.
Words in the context of the relationship matter which means that only serious threats can be successfully prosecuted.