It is often not evident as to how Marion's unique bonus works.
 
Here are some tips to help you understand the details:
 
    • Marion's bonus only applies to the full set of battle equipment; yet, if you equip two accessories of the same type, it will still apply.
      • These bonuses will get 1.5 boost if all conditions are met:

        Boost of guardsmen
        Boost of specialists
        Boost of engineers corps
        Boost of melee
        Boost of flying
        Boost of mounted
        Boost of ranged
 
    • Equipping items of different colors (rarities) does not affect the bonus.
 
    • Marion's bonus only exists where the hero exists; this implies that when Marion is marching, you will be unable to see the 50% bonus to equipment if you click the hero avatar and go to hero menu, since this menu displays Marion's bonuses as if he is in the city (recall that in fact he is not - he is marching).
 
  • You will see the bonus though if you click the hero icon in march menu.