12.2.4 - Strength User

Some Weapons do not have a fixed strength characteristic. Instead, they have Strength User listed or Strength +x. Where the Strength of a weapon lists User, you use the Strength (S) Characteristic of the attacking model equipped with the weapon. If the weapon lists Strength +x, you add the value of x to the equipped models Strength (S) Characteristic for resolving the models attacks with that weapon.