The Fate of the Arrow by Shel Pais

A young man, forbidden by law to even own weapons, dreams of becoming a knight to avenge the murder of his mother and defend his people. When he saves the life of the Baron of York, he abandons his old existence, blending in to learn new customs and maintain a dangerous secret. A conniving abbot learns the truth, threatening to expose the young man if his family does not agree to the abbot's hidden agenda. While earning the baron's favor and being relentlessly pursued by the baron's daughter, the aspiring young warrior must do everything to conceal his identity -- for he is not Donald as everyone knows him, but David, a Jew. And discovery would be fatal.