A knife can be used for buttering toast, slicing steak and, occasionally, for slitting  throats.
A gun can be used to hunt dinner, defend a homestead or shoot a rival.
Bare hands can knot laces, caress a woman or choke the life out of an innocent.

What makes us, humans, sometimes transform tools into weapons?

We are astonished when we learn about other animals being able to make and use tools.
Which is good. ‘Astonished’ is the opposite of ‘insensitive’. A.k.a. ‘brain dead’.

How about we, humans, learning from the rest of the animals how to solve whatever issues we have amongst us without  killing each-other?
You are aware that humans and chimpanzees are the only animals who systematically murder adult members of their own species, right?

But what instance is powerful enough to transform tool into weapon?

Human consciousness?

Is this a ‘fatality’?
The simple fact that each of us is consciously aware of the differences between ‘I’ and ‘all the rest’ means that whenever ‘survival instincts’ kick in our humanity necessarily vanishes? Entirely?
And ‘love thy neighbour as thyself’ becomes ‘dog eats dog’?

We would have already been dead by now… all of us…
Our ancestors must have discovered a way to balance our propensity to ‘stick with your own kind’ with with our need to learn new things and meet new people!
Or is it that some of us continually come up with fresh reasons for ‘war’ while we, the rest, are too lazy to do anything about it? Despite everything history has ever taught us…