A tent peg and a hammer.
To make things more sacrilegious, she killed him in the temple!
Point of information: Does the Bible consider this a murder or an act of war?
(singing) "If I had a hammer . . ."
The obvious answer, based on Judges 5, is that what Jael did was a wonderful, heroic thing. It was part of the war between good and evil. God was in the process of preparing for the coming of the Messiah and the enemy was set in its opposition to God. Their probation was at an end. He had given those peoples over 400 years to repent. God's patience is not infinite.
The gospel calls for us to take radical action also. It calls us to use "the nail and hammer", or knife, to cut sin out of our lives. If your hand makes you stumble, better to cut it off and get into God's kingdom with one hand than be lost with both hands. Don't put up with sin in our lives any more than Jael put up with Sisera. The "giants" in the land that we have to conquer are not people but sins in our lives that with God's power we can overcome.