ok, chill
I don't want your explaination side of it, I want the author explaination, specially cursed swords... whatever you come up with is not necessarily what's on Oda's mind...
and if you're out here to say "cursed swords" or "Oden's aura is still in the sword" or some other shit shouldn't be explained by the author and you're out here wanting freaking databook to explain it, I'm done