*Chapter 886 Spoilers
As we saw in the last chapter,
Luffy wants to see whether he can gain Katakuri’s CoO(Kenbunshoku Haki) ability. But is it possible that Luffy unconsciously used this ability before?
Katakuri generally can use CoO ability when he is calm and collected.
Below are 2 incidents when he used it:
In Marineford, Luffy unconsciously used his Conqueror’s Haki to stop Ace’s execution.
However, there was another incident in Marineford that was similar to Katakuri’s CoO ability.
When Luffy was fighting Hawkeye, he saw an image of his hands getting cut by Hawkeye, so he pulled them back and hit the ice instead. This might be a foreshadowing of Luffy’s CoO ability, and is quite similar to how Katakuri sees the near future.
Katakuri has to be calm in order to see the future, while Mihawk also states that Luffy is unusually calm at that moment.
Therefore, it is possible that Luffy might have used this future seeing ability before, but might have not understood it well enough. He may have unconsciously saw that vision of his future if he were to extend his hands.
The latest chapter also talks about how haki can be used up, particularly CoO. Luffy assumes that overtime, Katakuri, might have his CoO ability weakened if their fight prolongs.
Therefore, the state of Haki one has can change depending on how tired or exhausted a person can be. I am going on a stretch to assume that there could be a possibility that as you get to old age, haki may not be as strong as when you were younger.
This brings in the case of Whitebeard, and why he did not use Katakuri-like CoO or directly use Conqueror’s Haki on the navy, or to protect himself against Squardo of the Swirling Spider Pirates.
In the case of Squardo, Marco even mentions that Whitebeard should have been able to dodge his sword, even if he was an ally. He also mentions that his health may be the reason he is not able to dodge Squardo’s hit.
Therefore, I think that Whitebeard had this future seeing CoO ability that Katakuri had, and probably more haki based abilities that have not been shown so far in the manga. However, due to his old age and health conditions, he was not able to exercise these abilities in Marineford.
*Theory by MESS