Enma itself is an ass pull.
- Let's fight Kaidou on Wano.
- Oh what a ''coincidence'' that the only 2 blades that ever wounded Kaidou are also on Wano.
- Oh look! It's also a magical Haki sucking sword that boosts someones attack power beyond their own limit.
- Everytime Zoro attacked Kaidou with his 3 sword style, only Enma cut Kaidou.
- Enma is simply a ex deus machina.
Lets be real the only non ass pull power up that Trio got was Luffy's learing of Haki through battle and training, the existence of the RS for Sanji itself is a mystery when the fuck did his father show that he cared about Sanji to make him a RS, he literally thought he was dead until bounty appeared and even then he was gonna sacrifice him to Big Mom so no point of making a suit for him any way yet in the 2 days event from Saving their ass from BM' crew to escaping WCI his father made the perfect suit of Sanji that replicates the comics from years of the past.
Enma just like you said is an ass pull every thing it does is too damn suitable for the situation without it Zoro's Haki output would haven't been the same so he wouldn't have done as much damage to Kaido without it since he clearly didn't learn Advance Armament and still not aware of his CoC potential.