Sexy sword made to be snuffed.
Think about it.
Imagine a pristine, holy sword, given the greatest mission of the Weapons of Divine Teaching/Shinkai Makai/Shén Huì Mó Xiè - to actually actively hold back a slumbering Demon God. All the other blades, rusting away in shrines, could not hope to claim such glory, such honour.
But then, she's stolen away. Not by any ordinary thief, who wishes for gain, whether in power or gold. Instead, the Bones of Creation, in his hubris, believes only the finest blade may accompany his swordsmanship. He slaughters one of her guardians and sends the other on the run.
No, she begs, this is not what I was meant for. Return me to my rightful place.
And when the truth of her purpose is revealed, what happens? The man who took her laughs, a scumbag of a false hero ends up being the most heroic one there, imploring for her to be returned back to her rightful place. Only for 10guy and Kguy to make a deal, the former's ego putting mankind in peril.
In the end, it all ends in naught, as Rin Setsu A defeats 10guy, stealing his ethos as a swordsman.
And then 10Guy twists her beautiful form to pieces, metal screaming and distorting, and dies from the shrapnel. All just salve his ego after being humiliated by a duck.
Could you imagine the pain, the existential fear and desecration? Something, holy and pure, meant to stand above the petty squabbles of men, being dragged down and destroyed, out of a petty desire for revenge? Imagine...