Have you seen the hardening on Enma?
You see Zoro is not holding back on it because of some sucking ability.
He seems to able to control the amount of haki he uses on that sword pretty fine for now.
I said in chapter 1001 that SINCE THERES NO HARDENING, ZORO IS HOLDING BACK
And there’s your proof. Zoro said he will pull out more power and now there’s hardening
You’re the one who was saying we don’t need to see hardening to tell Zoro is trying a lot.
So in 1001, Zoro wasn’t using his haki and now in chapter 1002 he is.
So what’s the reason he wasn’t using haki in chapter 1001? Did he think he’d win without haki?