Defines how skilled a warrior is with their weapons in hand-to-hand combat, or how determined and vicious a creature is. The higher the score the more likely the fighter will land blows in [sic] a hand-to-hand combat opponent. An ordinary human has a Weapon Skill of 3. A battle-hardened Space Marine will have a Weapon Skill of 4 or 5.
Weapon Skill
Source: 3rd-A-Palooza (3.5) Rulebook v1.4, p. 2