weapon

arms, weapon, armament

这些名词均含有“武器、兵器”之意。
arms: 指士兵使用的具体的武器，如枪、炮等。
weapon: 普通用词，含义广泛，从随手可得的棍棒石头到各种枪炮，甚至原子弹等都可称为weapon，还可作引申用。
armament: 多用复数形式，指军队的武器装备。书面用词。

名词 weapon:

1. any instrument or instrumentality used in fighting or hunting
   同义词：arm, weapon system
2. a means of persuading or arguing
   同义词：artillery

1. The first exhibit was a knife which the prosecution claimed was the murder weapon.
   当庭出示的第一件物证是一把刀，据原告称是为谋杀凶器。
2. This weapon fires anti-aircraft missiles.
   这种武器是发射防空导弹的。
3. The fisher used a spear as his weapon.
   渔夫用矛作为武器。
4. Whether a gun is a weapon of offence or a weapon of defense depends on which end of it you are at.
   枪是攻击武器还是防御武器，要看你的目的而定。

weap.on

n.Abbr. wpn.（名词）缩写 wpn.
An instrument of attack or defense in combat, as a gun, missile, or sword.
武器：战斗中攻击或防守的器具，如枪、导弹或剑
Zoology A part or an organ, such as a claw or stinger, used by an animal in attack or defense.
【动物学】 袭击器官，防御器官：动物用来进攻或防守的器官或一部分，如爪子或螫刺
A means used to defend against or defeat another:
武器：用来防御或打败别人的手段：
例句：
Logic was her weapon.
逻辑是她的武器

v.tr.（及物动词）
weap.oned,weap.on.ing,weap.ons
To supply with weapons or a weapon; arm.
提供武器；武装

来源：
Middle English wepen
中古英语 wepen
from Old English wôpen
源自 古英语 wôpen