What??
Since when is the tiger hunt a mid attack? How do you know that that attack from king is high end? And why are you ignoring that Zoro only slashed the mask while King made Zoro cough uo blood?
Barrier haki or ryu is the haki that surrounds a sword or weapon and can be used defensively or offensively to increase the technique power.
I came to that conclusion by looking at all of Zoro's attacks. 300 billion world, death lion song, flying dragon blades and more are his high end attacks. Ogre slash, tiger hunt, and 720 lb Cannon are his mid-level attacks. Most of the two sword style attacks are his low end attacks.
I came to the conclusion that is a high-end attack for King because it's not only a Divine attack it also uses his beast mode physical strength to increase the technique attack power.
The attack itself didn't make Zoro bleed. He bled from going through the side of the giant's skull.