‘ And they slew of Moab at that time about ten eleph men, every lusty man and every man of valour. And there escaped not a man.'
Ten military units of men (five hundred upwards) who were there as guards to the king, and to put pressure on the subject people, were slain. All were trained soldiers and true warriors, but every one died to the last man. And Moab would now be too busy in determining the succession, in selecting and crowning their new king, which would take some time and possibly no little violence, to do anything about it.
“Every lusty man.” The word for lusty usually means fat. It may be that the writer is saying that the fat courtiers were slain along with the true warriors.
What are we to say about Ehud's method of using assassination? The king was an enemy of Israel and illegally demanding tribute from them. He was thus at continual war with them. So it was an act of war and as such legitimate. It was no more deceitful than laying an ambush for someone and enticing them into it.
It would have been a totally different thing had he paid assassins to kill kings who were merely ruling peacefully over their own countries. But he had not come as a faithful servant, professing loyalty from the heart, he had come as the representative of an oppressed people, and as one of them. And he certainly followed it up by showing that Yahweh was with him. ‘Yahweh has delivered' (Judges 3:28), and these are as much the words of the writer as of Ehud, for he unquestionably approved of them.