Vendetta's End Achievement in Guardian Heroes
Defeat Kanon in Story Mode.
How to unlock Vendetta's End
You encounter Kanon on stages 8,9,10,11 and 12. You need to choose only options 1-3 in order to fight him.
At the start of the match hit and then 5 times. This will select berserk mode for the undead warrior. Just hit again to set him in this mode for this fight. Now mostly block by pressing so you won't take much damage. If you get a opening you can use a projectile, but it isn't necessary. Mainly the undead warrior will do most if not all of the work and, he should go down in no time.