There are different ways to devour an Aragami:

• Just press  +  with a melee weapon.
• Press  +  after any melee attack.
• Press and hold  while using a melee weapon until an Aragami has fully emerged from your God Arc and release  to hit an Aragami.
• Press  to step forward followed by  +  with a melee weapon.
• Jump with  followed by  +  with a melee weapon.

Note: To unlock this trophy it's necessary to devour a living Aragami. It won't pop when devouring Aragami corpses.