I have no reason to suppose that he who would take away my liberty would not, when he had me in his power, take away everything else. And, therefore, it is lawful for me to treat him as one who has put himself into a state of war with me- i.e., kill him if I can..."[17-8]
Compare:
"If someone strikes you on one cheek, turn to him the other also. If someone takes your cloak, do not stop him from taking your tunic."
Luke 6:29
Locke is speaking about living in a pure state of nature where each man is an government unto himself.
Romans 13:4
for it is a minister of God to you for good. But if you do what is evil, be afraid, for it does not bear the sword for nothing; for it is a ministerof God, an avenger who brings wrath on the one who practices evil.
So therefore, in a pure state of Nature, where each man is an government unto himself, he surely has the same right to bear the sword as any other government has.