If STKM's head is touching a conductive material and you press down, it will spark that material, allowing STKM to activate certain machines (and I think STK2 has something similar). Moving solids (and, by extension, moving weapons with physics that STKM can use) don't exist in vanilla TPT.

There is a mod for stickmans. I do not remember their name but it adds shootable stick to stickman that can be toggled by pressing [Button] and has various ammunitions.

In case you do not use that mod, if stickman has touched neutron particle, press Down Arrow key to shoot neutrons, inflicting damage to other stickmans