the message of a ghost

This was an extremely powerful scene in all versions. In the Franco Zeffirelli version, Mel Gibson's emotion as Hamlet was powerful. We can see his desire to see his father's desire to to speak with his son. The ghost's first appearance was ominous. He appeared at 12 midnight and scared the guards with his mere presence. I believe he returned to his castle to check on it's condition. He predicted that, with it's king fallen dead, war would break out which would be why he returned with his old armor for battle. He returned later with his son and the scary, foreboding feeling was gone and a new desperate feeling arrived. The atmosphere that his father created as he approached his son was  full of desperation and an ominous cry for help. The tension in the moment created by the actors was what made this scene so powerful.