What is the last name of the person who had weakened technical mastery?  Answer the above question based on the context below:  During the 1950s, Szigeti began to develop arthritis in his hands and his playing deteriorated. Despite his weakened technical mastery, his intellect and musical expression were still strong, and he continued to draw large audiences to his concerts. In Naples, Italy, in November 1956, just after the Soviets crushed the Hungarian uprising, as soon as he walked onto the stage the audience burst into wild applause and shouts of Viva l’Ungheria! (Italian for "Long live Hungary!"), delaying the concert for nearly fifteen minutes.In 1960 Szigeti officially retired from performing, and returned to Switzerland with his wife. There he devoted himself primarily to teaching, although he still traveled regularly to judge international violin competitions. Top-class students from all over Europe and the United States came to study under him. One of these students was Arnold Steinhardt, who spent the summer of 1962 with Szigeti. He came to the conclusion that "Joseph Szigeti was a template for the musician I would like to become: inquisitive, innovative, sensitive, feeling, informed".Toward the end of his life, Szigeti suffered from frail health. He was put on strict diets and had several stays in hospital, but his friends asserted that this did nothing to dampen his characteristic cheerfulness. He died in Lucerne, Switzerland on February 19, 1973, at the age of 80. The New York Times ran a front-page obituary that ended with this 1966 quote from violinist Yehudi Menuhin: We must be humbly grateful that the breed of cultured and chivalrous violin virtuosos, aristocrats as human beings and as musicians, has survived into our hostile age in the person of Joseph Szigeti.
Answer:
Szigeti