I don't understand what you mean by this. As this chapter has established cursed sword are just swords with will that many are to weak to wield and understand. Enma was only draining Zoro because he didn't get what Enma wanted from him. Now that Zoro has fulfilled Enma's "task" bynot restraining his Haki anymore, instead giving it all of it, Enma won't act out against Zoro anymore.
Yes he is giving it his all which is why he saying he can died from haki lost or Oden was using more haki than him while using the sword .
We already know there stamina issue with haki .
This not about Enma any more this about Zoro saying fuck it and going all out with his haki sort like what luffy does with gear 4 .
This chapter is so fucking aswm and there was no particular show of who the best friend can be so I just have a feeling that its Sanji
but zoro calling him best friend is a little weird but kuina being the best friend is weirder as she wasn't his best friend at all... I mean best friend is a big word and at a time like this so that's why