The list is up-to-date (excluding holidays that always fall on a Sunday):
"The holidays observed in the Diocese [Sion] are equivalent to Sundays."
"The following are declared public holidays in the canton and are subject to the provisions of the aforementioned law: the holidays mandated by the ecclesiastical supreme authority of the diocese, namely: Circumcision (New Year), Saint Joseph, Ascension Day, Corpus Christi, Assumption of Mary, All Saints' Day, Immaculate Conception, Christmas."
"With regard to statutory deadlines or deadlines set by an authority within the meaning of this law, the following public holidays apply: a) the days stipulated by federal law [August 1]; b) the days stipulated in the cantonal Law on Sunday and Public Holiday Rest and its implementing regulations [New Year, Saint Joseph, Ascension Day, Corpus Christi, Assumption of Mary, All Saints' Day, Immaculate Conception, Christmas]; c) January 2, Easter Monday, Whit Monday, and December 26."
"The following public holidays apply: a) the days stipulated by federal law [August 1]; b) the days stipulated in the cantonal Law on Sunday and Public Holiday Rest and its implementing regulations [New Year, Saint Joseph, Ascension Day, Corpus Christi, Assumption of Mary, All Saints' Day, Immaculate Conception, Christmas]; c) January 2, Easter Monday, Whit Monday, and December 26."