The authors agree that Blasetig is a Slovene patronymic surname, derived from the name Blaže/Blažeta, a hypocoristic form of the saint's name Blasius (Saint Blaise).

E. Rossoni derives it from the patronymic in -ic or -ig of the Slavic name Blaze, Blazeta (Biagio), indicating the family of the sons of a Biagio, or from a dialectal diminutive in -utti, which would indicate the family of the son of little Biagio. He notes that Blasetig is very rare and typically Friulian; Blazetic is practically unique; and Blasuttig is very rare and specific to the Natisone valley, in the Udine area.

B. Zuanella specifies that the surname has been present in San Pietro al Natisone for about 200 years. On 17/8/1797, Jacobus Blasetig —born on 20/7/1773 in Kneža, parish of Podmelec, a hamlet of the Baška grapa near Tolmin— married Marina Strazzolini, of San Pietro; already a widower, he remarried on 20/9/1811 to Maria Jussigh. On 5/8/1799, Biagio Blasetigh, son of Antonio and Maria Drecogna, also native of Kneža, married Maria Capellaro, of San Pietro; a widower, he married on 13/6/1820 Maria Strazzolini. Zuanella describes it as a patronymic surname derived with the suffix -ič from the hypocoristic form Blaže (genitive Blažeta) of the saint's name Blasius (Saint Blaise).