Acts 12:2

And he killed James the brother of John One of the two sons of Zebedee, who had been among the three specially favoured disciples of Jesus. It is therefore likely that he would take a leading part in the labours of the Church, and so Agrippa's attention would be drawn to him as a proper person to be first struck down. All the accusations which had been laid against Stephen, that the Christian leader spake against the Temple and the Law, would be used with effect to such a zealous observer of Mosaic ritual as Herod Agrippa was.

with the sword This was the third in order of the modes of execution appointed among the Jews. These are stoning, burning, decapitation, and strangulation. In connection with the execution of James the words of the Mishna are interesting: "The manner of putting to death by the sword is as follows: the man's head is cut off with the sword as is wont to be done by royal command." See Surenhusius on Sanhedrinp. 238 (misprinted 248), where there is a discussion about the position of the prisoner, whether he should stand erect or have his head on a block.