I don't think that matches the common understanding of "weapon" in English. A sword, spear, gun, etc., is considered a weapon whether or not it is actually used

I don't think that matches the common understanding of "weapon" in English. A sword, spear, gun, etc., is considered a weapon whether or not it is actually used. An object not normally regarded as a weapon -- a walking-stick, perhaps, or a kitchen knife -- might become a weapon by virtue of its use as one. But military arms are inherently weapons, whether in use or not.