A12 Putting the Sword Into Its Place

How do we reconcile the wholesale slaughter of nations by Israel with the sword against the words of Christ? 

…for all they that take the sword shall perish with the sword. 

Not only men, women and children also. 

Deut 2:34  And we took all his cities at that time, and utterly destroyed the men, and the women, and the little ones, of every city, we left none to remain:

Were the Israelites truly in tune with the character of God? Why were they regularly afraid that He had brought them out into the desert to kill them? Was the deep darkness that fell upon Abraham in any way related to his taking of the sword to save his nephew and family?

Did the slaughter of the Shechemites by Levi and Simeon have any influence on the vow of Israel to utterly destroy their enemies?

The use of the sword by Israel is completely out of character with the life of Christ in the New Testament. How do we reconcile this apparent contradiction?