Monster Hunter World is both a beginner-friendly experience and a game full of appeal to its hardcore fans. With that said, some weapon classes appeal to one side of the spectrum more than others. The Dual Blades are an interesting case because both
beginners and experts can use them and have fun developing their skills with them.
The reasons for the Dual Blade's popularity are that they are extremely flashy to use, their combat systems are unique , and the damage is more than satisfactory when used correctly. With that said, there're certain aspects about the Dual Blades that just don't make much sense in terms of balancing, design, and in some cases, their overall usage in the game.

They Do Too Much Damage

One of the major philosophies of Monster Hunter weapon balancing is the tradeoff players have to make between mobility and damage. Usually, weapons that do high damage in explosive bursts tend to be heavier, limiting the player's ability to dodge and run around the monster. Dual Blades are a big exception to this rule, with seemingly no drawbacks.
The Dual Blades can deal more damage than perfectly charged
Great Sword attacks if the damage against the monster is optimized. The reason this is seen as an issue is that it makes it less desirable to play heavier weapon classes. If a Great Sword player has to give up their mobility in return for damage, and Dual Blade users don't, why even play Great Sword if the main goal is high damage?

No Regard For Teammates

One thing Dual Blades actually do sacrifice for their high damage output is range. The swords themselves are short, but the range reaches a bit further than the actual blade does. This means Dual Blade users have to get up close and personal with their opponents, forcing them to dodge enemy attacks with more precision.
The strange part about the Dual Blade's range is that when users perform the "demon dance" technique, the range of the swords seems to double and reach all around the user. Demon Dance is one of Dual Blade's strongest techniques that beginners can use since it only takes a simple combo for it to come out. The issue is that with that range, it becomes way too easy to stagger the allies around the user.
Staggering drains allies of their stamina bars and interrupts their combos, so it's the last thing any player wants to do. Dual Blades are among some of the most obnoxious weapons to be around as a team so its users should be conscious about where they swing their swords.

Heavenly Blade Dance Glitch

Heavenly blade dance is a signature move of the Dual Blades that has the character jump into the air and slice down the back of a large monster. The move is like something straight out of Attack On Titan and its animation changes depending on the shape and size of the monster. Because of how the animation works, it's pretty easy to bug the move out. RELATED: 10 Most Powerful Weapons In Monster Hunter World, Ranked
The glitch is most commonly seen in Elder's Recess on one of the crystal spires. If the player lures the monster to the spire and tries to perform the heavenly blade dance by jumping off the spire, the animation can clip through the spire itself. When this happens, instead of gliding along the back of the monster, the character will get stuck slicing the spire.
There aren't many glitches that can be done so consistently in Monster Hunter World , so this one stands out specifically.

Combo Routes

Monster Hunter World Dual Blade combos
Dual Blades have some of the most unique combo moves and special attacks. One of these special attacks is the demon dance technique which unleashes a flurry of blows to an enemy in a short period of time. The issue with using the demon dance is that it has an animation that can't be interrupted so the user is vulnerable while using it.
Normally players will use the demon dance when the monster has been stunned or trapped, so that it can't fight back, and they can capitalize on the opening. The reason the demon dance makes no sense is that it isn't even the Dual Blade's best choice for dealing big damage. Dual Blade users can cancel combos almost endlessly while maintaining their ability to dodge and evade, which does slightly more damage than using the demon dance.

Sharpness Management

Monster Hunter World visiting the smithy in Astera
The
sharpness issue is the biggest downside to using Dual Blades in Monster Hunter World. Sharpness provides a damage boost to blade weapons depending on how sharp the weapon is. As fights go on, weapons start to become dull, and their damage decreases due to low sharpness. Dual Blades have this problem more than any other weapon in the game.
The reason for this is that Dual Blades do a lot of hits over short periods of time, and each hit diminishes its sharpness. The penalty on sharpness is so severe that a lot of Dual Blade users look to skills like Handicraft to boost their sharpness and durability of the weapons.
The reason this makes no sense is that Dual Blade users have found ways to almost negate the sharpness penalty with certain builds so they act like normal bladed weapons. Many fans think that the combination of high damage and ease of use make Dual Blades a bit too strong compared to previous entries in the franchise. The sharpness penalty being negligible is another issue to add to the list of things that just don't add up in the Dual Blade's design.