Even before the law, righteous Abraham rescued his nephew with "trained servants," martial artists: Gen. 14:14--"And when Abram heard that his brother was taken captive, he armed his trained servants, born in his own house, three hundred and eighteen, and pursued them unto Dan."
We have a moral duty to defend the helpless: Prov. 24:11-12--"If thou forbear to deliver them that are drawn unto death, and those that are ready to be slain; If thou sayest, Behold, we knew it not; doth not he that pondereth the heart consider it? and he that keepeth thy soul, doth not he know it? and shall not he render to every man according to his works?"
According to the righteous warrior-king David, fighting skills are God-given: Ps. 144:1--"Blessed be the LORD my strength, which teacheth my hands to war, and my fingers to fight."
It is a common mistake to use Old Testament verses that line up with our own thinking, if we cannot accept what Jesus says about a subject. The problem is the OT was written for those under the curse. We are under Grace. Trying to combine the two can sometimes create confusion, and God is not the author of confusion. God tells us what OT scriptures to pay attention to:
Matthew 11:13
For all the prophets and the law prophesied
until John.
Luke 24:27
And beginning at Moses and all the prophets, he (Jesus) expounded unto them in all the scriptures the things
concerning Himself.
Luke 24:44
And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms,
concerning me.
Acts 28:23
And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God,
persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening.
Hebrews 1:1-2
God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets,
Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds;
"You say, but I say"
God never changes, but the way He deals with men did change.
From men under the Curse to believers under Grace.
From the Old Covenant to the New Covenant
Jesus made it clear we are to listen to Him, in opposition to the Pharasees who quoted OT script.
Matthew 5
38 Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth: (Old Covenant)
39 But I say unto you,
That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.(New Covenant)
A believer in the New Covenant cannot live by the Old Covenant and remain.