St. Paul was once a person who punished Christians and lived by the sword.  Jesus came to him and took his sight away.  When his site was later restored, it was done by a Christian who taught him to follow Jesus.  He came to understand what Jesus was telling people, and he was baptized.   Then Paul was asked to do three missions for Jesus. He went to Asia Minor and to Cyprus to set up Christian communities. He founded Christian churches in Galatia, a Roman province, and then Nero had him arrested for this work. He died by the sword, as Roman citizens did in that time, as a punishment for helping to spread Christianity.  He had done what Jesus wanted and asked of him, and he was martyred in Rome.  It seems fitting that he should then be the Patron Saint of Swordsmen.