This is the Catholic-Bible transliteration of 'David.' Protestant Bibles and most secular sources use 大卫. Encountering 达味 strongly signals you're reading a Catholic text - Sigao Bible, missal readings, or Catholic Church publications.
The classic underdog story from 1 Samuel 17, where the shepherd boy David fells the Philistine giant with a sling - a foundational image of the unlikely hero in Western culture.