After starting his career with Pro Gorizia in 1939, Blason made a name for himself with Triestina, making his debut in the Italian top–flight during the 1945–46 season. He was one of the main figures during the team's historic second–place finish in the league during the 1947–48 season, behind the famous "Grande Torino" side. He remained with the team until 1950, when he joined Inter, winning two consecutive league titles between 1952 and 1954. After a season with Verona in Serie B, he joined Padova in Serie A, where he remained for seven seasons, contributing to the team's third–place finish during the 1957–58 season.