When Lily was preparing to fight Naomin, she had a entire chat with Maverick about knowing her enemy as they used the same weapon. unless the entire thing was made up by gameforge, I doubt it was a translation issue.
Yes, both use scythes, but Naomin's weapon doesn't seem to be a Mist Scythe like Lilly's weapon. I think that was just mentioned because both were scythes, not implying Naomin's weapon was a SoulWeapon.
But, that's just how I saw it when I read that part of Lilly's story