Sceva may have been a chief priest or the head of a priestly family (cf. Acts 5:24), or he may have only claimed to be one. [1] Compare Simon Magus, who claimed to be someone great (cf. Acts 8:9). [source][source][source]
". . . whoever he [2] was, he was not a Jewish high priest who had held office in Jerusalem, since their names are all known; nor is it likely that he even belonged to a high-priestly family. It is possible that he may have been a self-styled "high priest" of one of the innumerable pagan cults, who found that it paid him to pass himself off as a Jew." [3][source]
Apparently two or more-the Greek word auton can mean "all" (NIV) as well as "both" (NASB) in Acts 19:16 -of Sceva"s sons participated in the exorcism that backfired. They were fortunate to have escaped from the house with their lives. [source][source][source]
"The name of Jesus, like an unfamiliar weapon misused, exploded in their hands; and they were taught a lesson about the danger of using the name of Jesus in their dabbling in the supernatural." [4][source]