an object such as a knife, gun, bomb, etc. that is used for fighting or attacking sb
a lethal/deadly weapon
The police still haven't found the murder weapon .
He was charged with carrying an offensive weapon .
something such as knowledge, words, actions, etc. that can be used to attack or fight against sb/sth
Education is the only weapon to fight the spread of the disease.
Guilt is the secret weapon for the control of children.
to be sth that has both advantages and disadvantages