When you kill an officer with an 8 or higher combo, the item they drop goes up a level - for example, if it was meant to be an attack+1, it will be a +2. Do this to 5 officers in a row to get this trophy. Most weapons can get 8 hits just from using repeated combos, but easier ones to try are the Sword (... is an 8 hit combo with a wide hitbox) or Halberd ( is a command grab with 11 or so hits, or is an string with 12+ hits). Or you can simply use a musou with high hit count. You can continue to combo officers after they are dead until they hit the ground.