The highly corrosive power of that black water was something like a whetstone. It looked like a grinder that could wear a diamond down into dust. It whirled continuously just outside the blue shield.
Night River King was confident in his Night River Beast God. The geno art didn't have overwhelming strike power like Yisha's Teeth powers, which could one-hit-kill almost any enemy.
But this corrosive and grinding power could destroy King class weapons. Even a deified item could be reduced to dust if Night River's attack bore down on it for long enough.
Night River King didn't believe Han Sen's shield was deified. And even if he did, with Han Sen's Marquise power, he wouldn't be able to use it at max capacity. Whatever the blue shield was, it wouldn't last long if Han Sen's rank was below the item's.