Albert Barnes Commentary 2 Kings 14:5

"And it came to pass, as soon as the kingdom was established in his hand, that he slew his servants who had slain the king his father:" — 2 Kings 14:5 (ASV)

The phrase, confirmed in his hand (2 Kings 15:19), usually expresses the authorization of a new reign by an imperial superior (see 2 Kings 15:19 note). Here, however, it describes the result when the troubles following the murder of Joash had passed away. The new king’s authority was generally recognized by his subjects.