According to the Chronicler, this verse means that everyone was ready to protect the king and the temple, standing with their weapons all around to keep them safe. It's like having your friends form a circle to make sure nothing bad happens to something important.
2 Chronicles 23:10: And he set all the people, every man having his weapon in his hand, from the right side of the temple to the left side of the temple, along by the altar and the temple, by the king round about. [side: Heb. shoulder] [temple: Heb. house]
This verse contradicts 2 Chronicles 23:10 as it advises putting away swords, while 2 Chronicles 23:10 describes having weapons ready at hand.
Matthew 26:52: Thinkest thou that I cannot now pray to my Father, and he shall presently give me more than twelve legions of angels?