Haki is an incredible power that exists within everyone in the world of One Piece, however, only a handful of people manage to tap into it. This power gives the user an incredible array of abilities, such as heightened sensory perception using Observation Haki, and the ability to improve both the offensive and the defensive powers using Armament Haki.
A rare third type of Haki that lets the user overwhelm others with their willpower, known as Conqueror's Haki, exists within one in a million people. Haki is a terrific ability to have up one's sleeve, however, if it didn't exist, the story would've been quite different.
10 Non-Devil Fruit Users Would Have Been Very Weak
Not everyone in the world of One Piece eats a Devil Fruit. In fact, the fruits are very rare in the four Blues and are even considered to be a myth. Those who don't possess Devil Fruit powers but fight at a high level, such as the likes of Gol D. Roger, rely on Haki.
However, if Haki didn't exist, they would certainly find it hard to keep up with the likes of those who have Devil Fruit powers and thus, would be at a major disadvantage.
9 Logia-Type Devil Fruit Users Would Be Almost Invincible
The Logia-type of Devil Fruits are extremely powerful, considered to be the strongest of the three main categories. These fruits allow the user to transform into an element or a force of nature at will, making them incredibly overpowered. Thankfully, Logia users' intangible bodies can be damaged with Armament Haki.
However, if Haki didn't exist, the Logia types would be almost invincible in battle. While they can be countered by other elements, some, such as Akainu's Magu Magu no Mi, are simply too powerful.
8 Devil Fruit Powers Would Work Without Restrictions
Devil Fruit powers are, at times, extremely overpowered and thankfully, Haki keeps quite a lot of their power in check. Essentially, a strong Devil Fruit user can still be countered by someone whose Haki is simply too powerful.
In a way, Haki keeps overpowered Devil Fruit abilities, such as the Logias or even the Mythical Zoans in check. Without Haki, Devil Fruits would work without any restrictions, and characters such as Trafalgar Law, who would then be able to slice and swap anything, would be unstoppable.
7 The Match-Ups Would Be More Interesting Without Haki
It is fair to say that the fights pre-time skip were slightly better than the ones after it simply because the concept of Haki was unexplored until the very end.
Without Haki, Devil Fruit powers truly shone and characters were forced to come up with clever ways to counter them. An example of this was seen at Alabasta, where Luffy used water to fight Crocodile's sand abilities and eventually, relied on his blood as a substitute when he ran out of water.
6 Shanks Would Not Be A Yonko Without Haki
Shanks is one of the Yonko of the Sea in the One Piece world and he's known to be extremely powerful. Although the true extent of his powers hasn't been seen yet, he was able to clash against Whitebeard on an equal footing and much later, stop Kaido in the New World as well.
Shanks doesn't have a Devil Fruit ability so he relies primarily on Haki in battles. His Conqueror's Haki is known to be especially powerful, however, without Haki, Shanks would be extremely weak when compared to the rest of the Yonko, all of which have tremendous Devil Fruit abilities.
5 Almost Every Straw Hat Would Have A Devil Fruit Power
The Straw Hat Pirates are the focus of the One Piece story and since Luffy aims to become the King of the Pirates, a certain level of strength is also demanded from every member of the crew.
While four members of the crew have a Devil Fruit ability, the others don't and down the road, that would've become a big problem. For this reason, it is highly likely that more members of the crew would've been given a Devil Fruit, especially the ones who fight a lot, such as Roronoa Zoro.
4 The Yonko Would Be Beatable Much Easily
The Yonko are some of the most powerful pirates in the world of One Piece and in all the cases, much of that is down to their Haki. Every Yonko seen in combat so far possesses high-level Haki that is extremely hard to counter.
The likes of Kaido and Big Mom use Conqueror's Haki coating as their main weapon in combat. Without Haki, however, they would be beatable much easily. A number of Devil Fruit powers would counter their powers without too much trouble.
3 Trafalgar Law Would Be Extremely Overpowered
Trafalgar Law is one of the members of the Worst Generation and an incredibly powerful pirate. Over the years, he's accumulated a bounty of 500 million berries, which is extremely impressive. Law possesses the powers of the Ope Ope no Mi, which is also known as the Ultimate Devil Fruit.
The powers of this fruit let him modify and operate on anything within ROOMs that he creates. Without Haki, this Devil Fruit would be impossible to stand up to, and even the likes of the Yonko would find it impossibly hard.
2 Gear Fourth Wouldn't Exist Without Haki
Luffy developed Gear Fourth during his two-year training on Ruskaina to combat the stronger enemies that he'd eventually face in the New World. Gear Fourth sees him utilize his Devil Fruit power along with the maximum output of his Haki to gain elasticity and increase the tension with compression in his attacks, making it extremely overpowered.
However, if Haki didn't exist, utilizing Gear Fourth would be simply impossible for him.
1 The Voice Of All Things Would Not Exist Without Haki
The Voice of All Things is an ability that very few people in the One Piece world possess. It is known to be even rarer than Conqueror's Haki and appears to be tied to Observation Haki. This ability allows people to hear everyone's voices, including animals and even inanimate objects. Every user to possess the Voice of All Things is, interestingly enough, a user of Observation Haki.
While that can be a coincidence in most cases, the fact that Momonosuke possesses this power and is only able to use Observation Haki implies that this power has some link to it. Without Haki, the Voice of All Things wouldn't exist.