All this talk about Enma this, Enma that. Yes, it's a blade that enhances a swordsmans ability but at the end of the day it's up to the master swordsman to control the blade. It's not a cheap upgrade as you have to be capable of wielding the blade.
I mean, do you mean to tell me that Yoru is what makes Mihawk the strongest swordsman in the world? Would Vista, Thunder McGuy, King or Zoro beat Mihawk if they traded blades? Would Tashigi beat Zoro if she possessed Enma?
Top notch swordsmen have top notch blades and each top notch blade, including Enma, has it's specific characteristics. Some draw out haki, others don't bend, some are incredibly light.
Shanks Gryphon and Rayleighs blade are sure to be top notch blades as well with their own perks. Gryphon is a christian symbol of divine power. Perhaps it's the world strongest blade imbued with CoC just like Yoru is the worlds strongest blade imbued with CoA? Ultimately it's the master swordsman that should get his dues for being able to draw out and controlling the immense power.