I explained Enma in detail:
I read your post about Enma. Was a very good one, but I commented after it why I didn't agree with some comparisons. Forgot to tag I think. So i'm gonna simplify what I wrote then.
Sandai and Shuusui indeed have the same theme of "being tamed" as Enma. Zoro have moments where he realizes that he needs to be able to control these blades. As you said, Whiskey Peak for Sandai, and Oars for Shuusui. But after these moments, it is just that. He later uses them normally.
Enma differs in some aspects. First, Enma is the one with the magical curse haki sucking thing. None of the others had that. He uses Enma once and his arm looks like was attacked by Crocodile sand ability. And he actively takes his haki back from the sword. That is something completely different from Sandai and Shuusui.
This was "the moment" when Zoro realized the had to "tame" Enma. Which many thought he did, since he was seen using it. (I particularly dont see any difference in the swords during my reading. I don't note the sheathe or whatever. To me, his blades were always "symmetrical". Didn't make a difference which one he was using, at least not for me).
Enma apparently makes a difference, because after using the 3 swords to cut Kaido, the only one he mentions later is Enma. And talks about drawing Enma's power. Like it was some Zanpakutou with a new form to unlock or something like that.
This is different from ALL of his swords. Not to mention that he still have the "hack" of Wado making it easier for him to wield Enma.
Weeks training and STILL didnt master it? I use this to say Enma is way above Shuusui, but people defend Shuusui being the stronger one.
If it is the stronger one, why is he having trouble with a downgrade THAT should be even easier because of Wado?
And it also implicates that Zoro need not to be stronget himself, but stronger blades. He alone cant become stronger, unless he have a new overpowered blade to master each time. This is how the story makes me feel. And I don't like it at all.
Zoro was the one getting stronger, and then he got swords that would catchup to his new power level.
Now its the opposite. Zoro is the one playing catchup with the new sword.
@Cinera