I just did a post in Reddit talking about this situation: The Reddit Post I just mentioned
I’m going to copy paste here and leave to others to contribue to the problem.
But overall: Dual Blades are lacking damage, they can’t compete with any other weapon for the end game.
Copy paste from Reddit:
"Have anyone ever soloed a 10 stars using one? I can’t find a video, I can’t find anyone that currently is farming 10 stars with DB.
The best I can find are g10 DBs being used to farm rank 8s and 9s at lowest difficulty, something like cutting 9stars Pukei tail or breaking 9 stars Jagras forelegs.
I challenged myself after complaining so much about DBs and currently I’m upgrading them all to g10. They feel SO DAMN WEAK. While other weapons absolute DEMOLISH lower rank monsters, DB still feels super weak vs them.
I have a g10.4 anja DB, g10.4 Legi DB, g9.5 Zino DB and a g8.5 Jyura DB.
On the other hand I also have a g10.4 black diablos bow, which kills absolutely almost anything up to 9 stars. And I’m using to farm 10 stars killing banbaroo as, which are super easy.
I also have a g10.2 Kulu LS and I used to some fights that bow struggles with. Like Tobi or Kulu.
Anyway… I ask again, have anyone ever seen someone soloing 10 stars using dual blades? And I mean LEGIT runs. I don’t want to see some BS video of a dude hitting all the PE while dodging with super delay by having cheat behind with hidden skills or hidden values etc.
Direct Link to the JP Leaderboards for 10 stars kills
Please help me. I can’t stand seeing DB being such a bad weapon and EVERYONE seems to not see that, wtf."
I learned that: 10 stars can only be farmed at Pukei (with a perfect run) or Banbaroo and Jyura with pretty good runs (does not require a perfect run). Odagaron is also killable, but requires luck with the attack pattern.
I would also like to add some honorable metions, from users replying to the thread:
"I was actually thinking about making a similar post, with the intent to discuss DBs and endgame.
I have 10.5 Legiana, Black Diablos, and Zinogre DBs, and 2 saliva away from g10 Deviljho DB, here are my main complaints:
Attack range is so short, even when I’m locked on the a weak spot, just the regular sway of a monster will cause me to miss.
Perfect dodge in demon mode (the whirlwind of blades) doesn’t seem to hit the part you’re locked on to, and the damage doesn’t feel great (also the animation is long)
Special ability is awesome, but the animation is quite long and it almost always puts you out of position, and can also easily miss. (Also doesn’t hit the part you want sometimes)
Demon mode dodging is a pain.
I don’t see how I can take on any 10* monsters right now. Maybe Pukei, but that needs to be a perfect run with perfect attack rng, and even then I doubt it (killing 9* at around 45sec)
DBs seemed fine early and late game, because you could over level to take on difficult monsters, but now that I’m maxxed out, they don’t seem as strong as other weapons. I’m by no means a bad player, not the best, and I know and use the high damage combos for DB, but I see LS and hammer taking on 9* & 10* monsters and think that doesn’t seem possible with whst I have."
From the User: u/StopItTickles
Another reply:
"Thought about making this same post, but every time I’ve tried to tell someone DB is far from S tier I’ve been downvote, because they’ve probably seen it 1 shot a 5* star with special.
But yes, you’re spot on. Just comparing other weapons and what they can do, it is obvious they are pretty bad. I actually think a good SnS player (that knows how to guard backhop rather than endlessly rolling away) can actually do more damage.
So here are my issues:
The damage: it just isn’t that good. I reckon it was about equal to Lance before Lance got decently buffed, I might still be being a bit generous there.
The special: it’s a double edged sword. Don’t get me wrong it is cool AF. The repositioning can be both a blessing and a curse, even if you’re clever with it (you can use it during flips like Rath and Zin on the head and you’ll actually start on the tail and ended up back at the head). Often you’ll end up quite a bit of way from the monster, so even if you’ve broken Raths tail, by the time you get to it then it’s recovered and stood back up.
Also, it sucks Vs Radoban because the damage is going into a lot of different armoured parts, unlike SnS where you can just special on the hind leg.
The reach: similar to SnS, you can lock on and somehow still miss when you’re practically inside the monster. If it does reach, with the way DBs seem to flail around, it’s surprising the amount of hits that don’t hit the lock on spot. When I played SnS I could always get triple break on Anja, I’m not sure I’ve ever got one DB. I’m sure I could find a way to cheese the third break, but it just shows how much damage is randomly going elsewhere. Also, been right on/under and had my special whiff, but I also had that with SnS so feel they are in the same boat.
Dodging: the damage while repositioning is a nice feature. However, I think this is why the overall damage is bad. Someone has thought that the idea of this is rather OP so have kept the rest of the damage moves lower. Unfortunately, whilst it’s nice, it really isn’t that strong. The side dodge is also more circular rather than a straight line, this is nice on something like Pukei, Rath, Lumu spin and allows you to stick to the monster. However, on larger monsters I’ve had times when it just gets “caught” on them so I ended up spinning in a spot to then get carted because it didn’t reposition me as it should, very frustrating.
P dodging: this is where it is outright bad. Firstly, both p dodges suck, demon mode or not. DM p dodge is the worst, the window to actually perform this is shorter than a regular p dodge so harder to time right and more likely you’re gonna get hit, but let’s just say you’ve practiced this like a god… well how do you get rewarded? You don’t. The damage is worse than using a normal spin dodge and repositioning. This is due to a combination of the MVs and how long the animation actually takes (it can be measured in days). On top of this, because the animation is so slow, if you dodge against the move you also usually end up out of reach of the monster. You can try to dodge with the attack, but this feels harder normally, and then you have the smaller timing window to do so. Regardless, it just isn’t worth it, you’re better of using the DM side spin to reposition and the 3 slashes afterwards. Not only will you do more damage, you won’t risk getting hit, and you don’t end up a mile away from where you want to be.
Demon Mode: the idea of this is great. However, not being able to turn it off when you have special is a nightmare. For example if you’ve entered DM with special ready against Diablos and she digs then you’re screwed because of the way the dodges will actually put you on top of her due to the circular movement.
General: For a weapon that is supposedly fast, the animation lock time is not. It feels like other much slower weapons don’t have you locked into an animation for as long. DB should have a lower animation time than LS, not longer imo. Because of this they don’t actually feel that fast and along with the low damage really takes away from the feel of the weapon for me. Also, due to the damage being bad you often have to go for the long combos or you don’t make it. This just leads to being locked in animation and risking being hit. DB doesn’t do enough damage to play too safe."
Reply from u/Kaesar83
Another reply:
"Thanks very much to everyone for their contributions to this post. I was actually just about to write a similar post entitled “why is my play so bad?”
I started on S&S, got Jagras, Anja, Tobi and Legi to 7-5, then saw how apparently awesome Dual Blades were, so I switched and got Jyura to 7-5, Zinogre to 8-2, Anja to 8-4 and Legi to 8-5 and still I cannot kill Level 8 monsters with any more regularity than once in a blue moon. I have Level 5 elemental armour for all of these weapons, with Lock-On, Burst and all of the recommended extras and still I cannot kill Grade 8 monsters. So if I have high level weapons and high level armour, the weak point has to be my crap play, right? Seemed to be the only option, but it might just be my crap choice of weapon, so thank you very much everyone for saving my sanity.
Of course, the problem might still be my crap play, but if anyone can give a recommendation of the current “best in field” weapon, I would be happy to switch.
I have other armour builds for Dragon, LBG, Partbreaker, Affinity and Focus, all at Level 5 or equivalent, and have idly been building up those weapons in parallel, but all of the few WGS that I have ever seen (almost all from quests) have gone into my Anja and Legi Dual Blades, so cannot yet get anything else to Grade 8. But happy to do the work if I am finally going in a good direction.
It is a delight to see other people’s videos of soloing 8* Zins and 10* Blackies, but really frustrating for me to keep losing lives and running out of time against Kulus, Girros, Pukeis, Tobis and Banbaros when I am in theory so heavily armed and they are in theory so easy to kill. Everything else, no chance at all 
"
This from: u/martinuwh
This is the current situation for the DB.
Lance had a similar problem before, but they tweaked some attacks, gave them a buff.
Same happened withe LGB, with also new equips that had them stronger by giving r3/r3.
I don’t think equips will help DB get the dps check.
They might need a push like LGB got it or even a tweak in the weapon attack sets to make it even, like the Lance got one.
Just please don’t come here saying the weapon is stronger, the numbers are out there, they look cool etc etc etc. There are plenty of users that did this already, the game is not that simple, the weapon is far more complex that only numbers big win.
Thank you for your time.
I hope this helps giving the weakness of Dual Blades awareness.
monsters no problem, and if it is, I suggest learning the weapon more instead of trying to convince Niantic that this is the weapon they need to reball, instead of SnS