The Strong Prince

Once upon a time there was a king of one land. He was a stupid alcoholic. Every affair in the kingdom went to rack and ruin. One day he was dead. Despite his drawbacks, he was very kind to his family - his wife and son mourned his loss bitterly. They abandoned the crown and forsook their country. At length they wandered into a forest and the mother told to the son that she wanted to drink and sent him to seek some water. The son found a stream with water and in the reflection of a water he spotted the golden sword that was hanging upon the tree branch. On its handle was written: 'The man who can buckle on this sword will become stronger than other men.' What the prince would do with the sword? What happened next?