[quote=@Session]
<Snipped quote by Path>

How’d it get corrupted? And what’s it do?
[/quote]

They said that the ore was “bled” out. Possibly using forms of dark magic and killing. The mythril blade is good all adventurers as it is versatile while the corrupted one is good for killing. 
*looks at you*
It draws from the mana [i]and [/i]life force one has to create a stronger output. For some reason that blade has an effect on living beings, like it feeds on them.
*looks at Gio*
When using it, it is ideal to use it against living beings as it is a way to work around its cost.