Here is the full list of all 14 BackSlash achievements.
Fully dismember an enemy summoner when finishing him.
Beat the great master Oji.
Win at least three duels in survival mode.
Get rid of a feng blade with a sword attack.
Parry incoming bone shards with a shackling root.
Unlock the eleven styles.
Get at least 55 stars from the quest mode.
Win at least seven duels in survival mode.
Make a total of 352 duels.
Win at least eleven duels in survival mode.
You somehow killed an innocent little bird...
Your fights destroyed at least 1000 rocks.
Perform successfully a seven big melee attacks combo.
Find and save my childhood buddy.