You could absolutely make a point that bow and arrow could be a defensive tool; but it's primarily usage was to hunt animals and to fight in war, both of these actions are offensive moves..unless you take bow and arrow to defend yourself against a charging army.

Shield alone doesn't defend. Otherwise every police office in US would be wearing just the shield. Are you suggesting that the primary reason for the guns in hands of the cops is to kill criminals? Nope.

There are over 300 million guns in the hands of citizens in United States, are you saying each of them bought it to kill people? They bought it primarily to defend themselves. First of all, a gun acts as a deterrent and balances the power. If the culprit still doesn't back off and is going to put the gun-holder's life in jeopardy, then the gun owner pulling the trigger is not killing the criminal, but defending self. If you think this is bending the truth, I don't know what truth is.

Ever heard of the phrase in sports, Offense is the best Defense (and vice versa)?