“‘They have blown the trumpet, they have made all things ready, but no one will go into battle, for my wrath is on the whole crowd.

and he sees the sword coming against the land and blows the trumpet to warn the people,

then if anyone hears the trumpet but does not heed the warning and the sword comes and takes their life, their blood will be on their own head.

Since they heard the sound of the trumpet but did not heed the warning, their blood will be on their own head. If they had heeded the warning, they would have saved themselves.

But if the watchman sees the sword coming and does not blow the trumpet to warn the people and the sword comes and takes someone’s life, that person’s life will be taken because of their sin, but I will hold the watchman accountable for their blood.’