There will be a second sign. Saul will come to the plain of Tabor – this has nothing to do with Mount Tabor; we have no idea where this Tabor was, but it's clearly a different place.
This is a message to us, and particularly to pastors, to office bearers. We are to remember the history of God's people, to remember our own salvation and how God has dealt with us down the years, to stay close to the word, to live simply, to remember that we are servants: servants of the Lord, servants of the people we have the opportunity to witness to and to reach and to minister to. Ministers are not heroes, not special people, not rich people. They are dependent upon the tithes of their fellows, brothers and sisters, living reasonably. These signs are full of lessons. Yes, they authenticate the message of Samuel that he is anointed to be king, but they do so in a way that at the same time instructs him.