1) Zoro's Ushi Bari isn't a cutting technique, when he uses it he try to hit the opponent with the point of his swords. So definitely it's like a blunt attack.
And yet he didn't manage to damage Mr. 1 with this technique
2) Mr. 1 himself said that he blades and blows doesn't affect him. You have to be a lot stronger than him if you want to hurt him with blows and blades without haki, I dare say at least at CP9 level.
This is Wootz Steel, it was used in India before the middle Age, modern steel is way harder