Although Oda keeps many secrets about the origins of Haki under wraps, he has subtly revealed its greatest weakness through events involving Yonko Big Mom and the legendary pirate Rocks D. Xebec.
The biggest weakness of Haki is hesitation and doubt
Haki plays a huge role in One Piece and will only grow more crucial in the Final Saga. While much about Haki remains a mystery, Oda has clearly illustrated deep secrets about this power, even if not everyone notices.
Just as he highlights Haki’s greatest strengths, Oda also reveals its biggest flaw: doubt and hesitation. When these creep in, Haki weakens and becomes vulnerable. This is a point Oda repeatedly emphasizes.
To understand Haki’s greatest weakness, you need to grasp its true nature. Haki isn’t a special power like a Devil Fruit ability. Instead, it’s something everyone in the One Piece world possesses. Haki exists within each person because it represents their spirit and willpower.
As Silvers Rayleigh told Luffy: “Never doubt, that is true strength.”
Seeing Haki as a manifestation of spirit and will makes everything clear. Haki allows a person to sense emotions and even glimpse the future. Through intense training, one’s spirit sharpens enough to predict attacks or sense true feelings.
Similarly, Haki can nullify Devil Fruit powers on contact, which can be explained by the same logic. When someone masters control over their spirit, they can attack another’s mental state. This explains why Haki falters when doubt and hesitation arise.
Years ago, during the Whole Cake Island arc, fans wondered why Big Mom, who constantly surrounds herself with Conqueror’s Haki, was hurt when her Mother Carmel photo was destroyed. The answer is simple: breaking the photo shattered her mental state, weakening her Haki to the point where she could actually be harmed.
Similarly, when Katakuri fought Luffy and Luffy uncovered his secret, Katakuri’s panic and hesitation caused his Haki to falter, allowing Luffy to land hits.
When Garp fought Kuzan, he easily overwhelmed him. The only thing Garp said was “hesitation is weakness.” This also explains why Rocks, despite his powerful Haki, was easily defeated by Imu’s Domi Reverse at God Valley. Rocks hesitated because of his wife and son, allowing Imu to overpower his Haki and successfully use Domi Reverse. When Rocks tried to resist, Imu mentioned Harald, another weakness of Rocks, and manipulated him successfully.
Unshakable belief brings the strongest Haki
Only those without hesitation possess the strongest Haki, and those with the strongest Haki cannot be defeated.
When you look at Haki at its core and understand it as spirit and willpower, it’s easy to see why those with unwavering belief, like Luffy and Roger, reach the pinnacle. They never hesitate and have no doubts about what they want to achieve.
In particular, Luffy never hesitates, which is why he will conquer the seas and become the Pirate King.