With only a blunt knife, relying solely on the inherent smoothness of the blade and following the grain of the wood, he split it in two, a clean cut all the way through!
How does one use a knife that is not sturdy to cut through desired objects without damaging or degrading the blade itself?
And how does one wield a knife in the midst of thousands of soldiers, battling to the end, and still find it usable?
How does one manipulate a blade when facing an enemy stronger than oneself, using the features of the enemy's weapon to suppress with the characteristics of the knife?
Until at last, a 'natural air' of 'with a blade in hand, I am invincible' sublimely emanates from within the heart.
It is an accumulation bit by bit.
Only when one is extremely familiar with the knife in hand, and uses it to win a hundred battles, can such a momentum emerge!
In this person's hands, any part of the blade can be utilized, all can kill, all can slaughter!