Later when duel are available people will whine, why this class so OP than this class and so.
And the challenger who lose from fight might be butt-hurt and rant at the forum.

I think DEV already think about this but they not ready yet for it.

I'm OK if they make another separate server for PVP and have everything about player kill player thingy on that server, I will make another character there... But don't add duel to the current PVE server I'm to lazy to deal with it, this character is purely PVE.