Wishi-washi Wakizashi 

legends tell of a sword that was crafted to kill a god. the swords makers sword is stuck to the sword.

This is not that sword

 This is the Wishi-washi Wakizashi made by a his brother who needed a knife to cut cloth he ended up cutting his finger and died his soul was bond to the sword

(when the user misses they told off by  Wishi-washi and gain disadvantage on next attack until they hits) 

Proficiency with a Sword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Slashing, Finesse, Versatile