This is a super-power that reflects your character’s ability with weapons. You might have a specific weapon that you own, like Thor’s hammer, Daredevil’s billy-club or Captain America’s shield, OR you might simply be good with all kinds of weapons, like Wonder Woman, Deadpool, Bullseye or Deathstroke.
Normally, if a character picks up a random sword, baseball bat or gun, it would be an Advantage and either +1 dice for 3 actions or +2 dice for one action (as per normal Advantage rules). The powers on this allow the Weapon Master character to exceed that.
Download the complete Power-Set here: Power-Weapon Master