The Ryūye is a sword made by a swordsmith to pray for the immortality of his beloved daughter and enshrined in the lake.
It is also the weapon in which the swordsmith sacrifices his body in order to forge the most perfect work in his life.
He was born to protect his master and pray for his eternal life.
So, how can one watch the owner being injured and remain indifferent?
The sharp blade with an unknown name can bring peace to its owner.
There's nothing wrong with this logic.