Great devil fruit with terrible users in one piece

Technically speaking, there is no such thing as a weak Devil Fruit. The potential for each to be trained and in some cases awakened after a certain point is always there. That being said, there is absolutely such a thing as a weak Devil Fruit user.

While certain seemingly harmless materials such as string or mochi can become a lethal weapon in the hands of the right fighter, the opposite is also true. Sometimes a more evil user can pull down a Devil Fruit that at least has potential if nothing else. These users are usually bad fighters, and their weak natural abilities can undermine even the great ones that Devil Fruits allow.

5 Buggy

Failure falling up

• Debut: Chapter 9 (Manga); Episode 4 (Anime)
• Devil's Fruit: Bara Bara no Mi
• Devil Fruit Class: Paramecia

Buggy is probably the poster child of skinny pirates. His infamy is often only due to those he associates with, and his real strengths lie in brokering alliances and convincing others to fight for him. Even his rank as a figurehead in the Cross Guild, the position he had most recently forced himself into, resulted in power being reclaimed from the true leaders, energizing his crewmates to get excited about making him Pirate King.

However, his own lack of skill as a fighter can cause one to overlook the potential that the Devil Fruit actually has. Even though Buggy doesn't fare too badly, having the ability to survive being cut and disassembled still works well with his own hacking style, a more combat-oriented pirate could probably make better use of it. The Devil Fruit's extended range, ability to survive numerous cuts, and potential for improvisational combat could all be devastating in the hands of a more experienced fighter. However, for Buggy the Clown, they are more appropriately classified as comedians.

4 Pierre

And the most redundant devil fruit goes to…

• Debut: Chapter 237 (Manga); Episode 153 (Anime)
• Devil Fruit: Uma Uma no Mi
• Devil Fruit Class: Zoan

Pierre is not a particularly poor fighter. He is the long-time companion of Gan Fall, the god of Skypiea, and bravely accompanies his master into battle. Using his Devil Fruit, he can transform his body into that of a horse, serving as a mount for Gan Fall as he rides his winged companion into battle. To the uninitiated, this may seem like a beneficial fruit of the Devil for Pierre.

The only problem? Pierre was already big enough to fit Gan Fall in his bird form. While the aesthetic of a pegasus that Pierre conjures can be admired, it ultimately has little to do with his own fighting style, save for the occasional bite he can deliver to someone in horse form. A human being or even another animal that could benefit more directly from a horse's assets would be a better choice than a bird that may already be mounted by its owner.

3 Funkfreed

A sensitive sword

• Debut: Chapter 365 (Manga); Episode 254 (Anime)
• Devil Fruit: Zou Zou no Mi
• Devil Fruit Class: Zoan

The Funkfreed is, in its basic form, a rather large sword owned by Spandam, the former leader of Cipher Pol 9. Spandam's position in CP9 was given to him by nepotism rather than skill. He is an infamously poor combatant, perhaps one of, if not the worst in the series. His only means of self-defense is the same sword, which he is not skilled in using. However, through unknown means, this llama managed to “eat” a Zoan Devil Fruit and gained sentience, along with the ability to transform into an elephant.

Unfortunately, Funkfreed is as cowardly as its owner. It may be able to knock people out or overwhelm people in a select few cases. That being said, it took quite a bit of effort on Franky's part to turn the sword against its owner, even though it was in elephant form. Some might attribute this to the Devil Fruit itself, as Zoans are said to have minds of their own. That being said, if a user comparable to Jack the Drought (using an old variant of Zou Zou no Mi) were to eat this Devil Fruit, they would likely become a much bigger threat than Funkfreed.

2 Gecko Moria

Carried by His Devil Fruit

• Debut: Chapter 449 (Manga); Episode 343 (Anime)
• Devil Fruit: Kage Kage no Mi
• Devil Fruit Class: Paramecia

Gecko Moria is a somewhat terrifying enemy. He can manipulate the shadows of others, create a number of powerful minions, and is able to augment himself with shadows to increase his size and strength. That being said, for all his skills and reputation, Gecko Moria is pretty poor as a pirate once the Devil Fruit is taken into consideration. Since his defeat at the hands of Kaido, which resulted in the deaths of his former crewmates, he has instead decided to become the Pirate King, particularly relying on others. He often uses his Devil Fruit to manipulate his own shadow to fight for him, and shows much more enthusiasm for guiding others to fight for him.

His own difficulty dealing with the Straw Hats at Thriller Bark led to his colleague Kuma being directed there against Moria's will to deal with the problem instead. He was eventually coldly dismissed from the Seven Warlords of the Sea for his incompetence. Doflamingo was accused of executing him unsuccessfully during the Summit War. Jimbei, another former War Lord, noted that Moria had weakened due to his lack of training. Recently, Moria and his crewmate Perona escaped the clutches of the Blackbeard Pirates. It remains to be seen if Moria will try to make himself more worthy of his Devil Fruit powers.

1 Kurozumi Orochi

Scattered A Mythical Zoan

• Debut: Chapter 927 (Manga); Episode 921 (Anime)
• Devil Fruit: Hebi Hebi no Mi, Model: Yamata no Orochi
• Devil Fruit Class: Mythical Zoan

Kurozumi Orochi is not primarily a fighter. Although he shows some skill with a weapon, he is an overall inferior combatant compared to Kozuki Oden and has created propaganda to counter this fact. He took advantage of Kaido's power to become shogun and instead used the Beast Pirates as well as his own servants to intimidate others into obeying him. When Kaido no longer saw any use for the selfish Shogun, he beheaded him in an attempt to directly usurp his political power. That being said, Kaido failed, due to the stupidly good Zoan Devil Fruit that Orochi consumed. Orochi's Devil Fruit allows him to transform into the legendary Yamata no Orochi, an eight-headed serpent from Japanese mythology.

Having seven extra heads is somewhat excessive, even if it reflects the character's own hidden serpentine nature. Orochi was decapitated six times at once by the nine red sheaths. His last head (and his body along with it) died after being cut off by Denjiro and later burned alive by Kozuki Hiyori. Although Orochi managed to survive the event of his defeat, it's possible that a truly competent fighter would have managed to survive with at least a few more heads intact.