We have:
+ Zoro: "I need to unleash more of Enma."
+ Kaido: "Oden..."
+ Big Mom: "That sword is not normal."
+ Enma: I have a weird Aura around me.
+ Zoro input his Haki -> Weird aura powered Enma.
How can you think Enma doesn't have special powers after this? I'm really baffled.
Zoro wished to unleash more of Enma either in that he had not mastered the sword or because it's somewhat better than Wado AP wise but his power prominently derives from his own training. Enma is just an O wazamono sword, not even Supreme Grade, there's no evidence of it being so powerful AP wise. When Zoro blackens Enma at least it will change grade. But don't expect a mastodontic differential.
Kaido meant Oden's presence, not haki, that has nothing to do with AP but the memory imprinted in the sword, living object.
Big Mom was probably referring about the AP of Zoro rather than the sword because sensing the astounding energy the sword was emanating thanks to Zoro's haki, that's the most plausible explanation because she probably didn't know shit about Enma and its history.
It's very easy, well at least for me.