Anything can be used as weapons, but some common ones are:
people
See the question: What are some weapons used in the middle ages?
tactical nuclear weapons
some new weapons that were used were the machine gun, the tank, the flamethrower, and the Airplane was now used for battle
They used missiles, bombs, fuel-laden planes, and biological weapons.
Some weapons that the ancient Incas used were slings and spears. They also used axes and bows and arrows.
some gun
the used some thing
The most common weapons that were used by (ancient) Greek soldiers were the spear and the sword.
Some of the countries have nuclear weapons because they use them as a defense mechanism. The nuclear weapons are intended to be used whenever there is a war.
AK47
- some viruses can be used in biological weapons- some viruses are used in the fight against pests