Such a familiar tone. But Larian bla bla bla.
How is it made stronger by the GWM? It rerolls the DAMAGE die not the ATTACK one. How are they even connected??? Lol. What items are you referring to? What weapon actions? Battle master maneuvers? You are almost always better taking +1 AC and equiping a shield for riposte action milking. Dueling adds straight +2 on the damage die, while GWFS adds less than average one DMG on anything but greatsword and mauls. Two weapon fighting style adds your modifier as damage which is +3 and more STRAIGHT damage. Sorry for using all caps but you said something extremely vague and ridiculous at the same time.