Jabulkheir made a thread about this misconception here : https://twtext.com/article/1380956539519913984. His main idea is that CoC is actually latent within EVERYONE !!!
Here is the core of Jabulkheir's theory : "Taking Rayleigh's comment 80 chapters later, Conqueror's Haki is a MANIFESTATION of someone's spirit. Once someone's will reaches a certain level of conviction or determination. A person's will is what unlocks conquerors in a person. THAT'S why it cannot be trained, but only controlled. One cannot train his own resolve or heart. It's said Conquerors is common in people that make a big name for themselves which is TRUE. That's bc those peoples conviction in rising up or achieving their goals was strong enough to the point their will manifested as CoC, not vice versa. CoC can only be unlocked and strengthened by ironing your will further, NOT smth ur born with."
When she talks about mastery, it can't just be about knocking the weak off on purpose (like Luffy did on FMI) since it doesn't make much of a difference than when it's done unconsciously.
She was referring it at just spirit, so I guess she knows about Adv CoC ... since her sister is probably one of the most effective CoC user in the world (Coby has no damn chance against her ).
What ? Does this mean there's other types of CoC ? What could they be ?
Among all CoC users, they all have in common the CoC wave which causes weak spirits to faint, black lightning strikes, and those black flame sparks when Adv CoC is used. All but one ... Zoro !
While everyone affects the environment with their CoC, Zoro's one seems to only act on himself since he is able to manifest limbs out of nothing. He is the only one we have seen to have such a CoC technique.
It's as if there are 2 kinds of targets when it comes to using CoC : conquering one's self (Zoro), conquering the livings and the world (Luffy and the other users).