Oda made a clear distinction between CoC outburst and CoC coating. In ch 1001 of the rooftop, Kaido's Thunder Bagua had a CoC outburst, which is characterized by black lightning surrounding the target. In ch 1010, Kaido's Thunder Bagua had lightning streaming out of his weapon, which was then characterized as CoC infusion. Zoro's Asura, which also had an outburst of CoC, wasn't included in the sentence of "only a handful are capable of doing this", it was only being addressed when Luffy pointed it out about Kaido.
Now one might ask, what the difference between CoC outburst and ACoC is, as Oda didn't make a clear distinction outside the visuals. You might argue that it is just an intermediate step, an incomplete weaponization of CoC.