NieR. It is given to Nier as a gift by the King of Facade after he saves him from the Barren Temple.
"A unique sword with a round blade. Legend holds that it robs the wielder of his life force."
You see this? This here is for me to cut your life away. There's no need to panic, it won't hurt at the beginning. Later, though, I'll make you feel the worst pain imaginable. And nobody screams at the pain. Just when they see themselves bleed, first.
But I'm not going to let you off so easy. This part of the blade here is very sharp and painful, so it's only for after I've had my fun. And your voice will go hoarse like that, and become loud and unintelligible. How irritating...be quiet, or my hand just might accidentally slip.
Don't worry, I'm not going to kill you. Yet. The fun part is drawing all the pain and suffering out as long as you can. You see, humans are surprisingly hard to kill. And besides, we all have two eyes...two ears...twenty digits...and one hundred and forty-four joints. We can take our time.
You ask me why I'm doing this? Heh...this is all because of you, don't you know? You're the one framing and torturing your people. You're the one putting their bodies out on display. Oh, you don't remember? Then I'll just make you remember each and every thing you've done to my family, one, by one, by one. Hahahahaha...