Summary
One Piecehas no shortage of powerful characters who are renowned throughout the world for their strength. Most of these characters are endowed with extremely potent Devil Fruits that can turn the tide of battle in the blink of an eye.
These individuals are heavily reliant on these powers, and they only focus on improving them. As a result, the other possible weapons in their arsenal end up suffering. Haki is something that every character can potentially awaken and master with good training. However, certain strong characters end up ignoring it, causing their Haki to become extremely underwhelming.

7Whitebeard
Old Age Made Him Weak
Whitebeard was one of the Yonko and the captain of the Whitebeard Pirates. He was known as the strongest man in the world, and it was mainly due to his incredible physical strength and Devil Fruit power. Whitebeard possessed the Gura Gura no Mi, a Paramecia-type Devil Fruit that allowed its user to create tremors at will.
In his prime, Whitebeard was able to use all three types of Haki effortlessly but lost control as he got older. During the Marineford arc, Whitebeard was extremely sick, and he couldn’t even use any of the advanced versions of Haki.

6Crocodile
Lost To Luffy Despite Having Tremendous Experience
Crocodile is the co-founder of the Cross Guild, which is considered the biggest threat to the Marines. Crocodile was introduced in the Alabasta arc, where he defeated Luffy three times. He possessesthe Suna Suna no Mi, a Logia-type devil fruit that enables him to create sand at will.
Despite being an experienced fighter, Crocodile Haki was hardly impressive. He was unable to use it when Luffy took him down in Alabasta. A lot of time has passed since he was last seen in action, so it will be interesting to see whether his Haki has improved or not.

5Gecko Moria
Let Himself Go After Losing To Kaido
Gecko Moria wasthe main antagonist of theThriller Bark arc. The Shichibukai resided on his massive ship with a zombie army and other top officers. When he was at his zenith, Moria was able to fight on equal footing with Kaido. It is obvious that his Devil Fruit power wouldn’t have been sufficient, so Moria’s Haki must have been the top draw.
With time, Moria became more dependent on his Kage Kage no Mi. Due to this reason, his physical abilities and Haki suffered a massive drop. If he were still training, Moria would have had no trouble dispatching Luffy in their fight.

4Portgas D. Ace
Did Not Train His Haki Too Much
Portgas D. Ace was one of the most promising rookies of his generation. Not long after setting sail, he managed todefeat a Shichibukai, andsubsequently, he received an invitation to replace the person he defeated. Ace refused the offer and eventually ended up as the Second Division Commander of the Whitebeard Pirates.
Ace’s fame continued to grow, and his Mera Mera no Mi had a big role to play in it. A single attack powered by his Devil Fruit was potent enough to destroy a town. However, Ace’s Haki was not too impressive. While facing Blackbeard, he couldn’t use it to defend himself. Furthermore, Ace’s Busoshoku Haki was unable to help him fight Akainu. If he had better Haki, Ace could have countered Akainu’s Devil Fruit ability for sure.

3Donquixote Doflamingo
Exceptionally Weak Haki That Was Bypassed By Law
Doflamingo used to be the king of Dressrosa and a former warlord of the sea. He was a ruthless individual who only cared about achieving his goals. To him, everything else was secondary, including the lives of his own family members.
Doflamingo had immense control over his Ito Ito no Mi. He could use it to control the movements of other people. Due to his overreliance on his Devil Fruit, Doflamingo’s Haki was extremely average. This was evidenced by the fact that when he tried to grab Law’s sword, he ended up cutting his hand.

2Trafalgar Law
Too Dependent On His Devil Fruit
Trafalgar Law is one of the more talented members of the Worst Generation. Due to his alliance with the Straw Hat Pirates, Law received a lot more screen time than the other Supernovas. Law possessesthe Ope Ope no Mi, a Paramecia-type Devil Fruit that has the power to create ROOMs.
In Wano, Law had to fight Big Mom alongside Eustass Kid. Both of them were unable to harm her, but that changed once they began to use their Devil Fruit Awakenings. In the fight, Law did most of the heavy lifting, and without his overpowered Devil Fruit, they would have lost to Big Mom. The two were lucky that Oda nerfed Big Mom on purpose by not letting her use Conqueror’s Haki. Following Law’s success, he journeyed to another island, but he was caught and defeated by Blackbeard.

1Eustass Kid
Was Easily Demolished By Shanks
Eustass Kid was the captain of the Kid Pirates. He was a Supernova with an impressive 3 billion Beri bounty. Kid was heavily involved in the Wano Country arc, where he teamed up with TrafalgarLaw to defeat Big Mom.
Kid’s Haki was so mediocre that he was unable to deal any damage to the Yonko. It was only after he used his Devil Fruit Awakening that Big Mom was hurt. His weak Haki was once again on display when Shanks single-handedly wrecked Kid and his crew. To add insult to injury, Dorry and Brogy destroyed Kid’s ship.
