In terms of physical strength, Tengen Uzui is far from being the weakest Hashira. While his feats throughout the Daki and Gyutaro battles certainly displayed this, there's additional evidence to show that he's not the weakest Hashira.
Demon Slayer's Tengen Uzui is considered to be one of the weakest Hashira due to almost losing this fight, but the fact is that Tengen only looks weak when compared to the most overpowered Hashira.
8/13 Shinobu Kocho, The Insect Hashira
That being said, she's arguably the weakest Hashira when it comes to pure strength.
So to cut a long story short, Kyojuro Rengoku is more powerful than Tengen Uzui. Among the Demon Slayer Corps, Kyojuro was acclaimed as a skilled combatant who was always dedicated to fulfilling his duty as a Hashira.
2) Sanemi Shinazugawa
He dedicated all his time and effort towards perfecting his skills as a swordsman which was shown during the fight against both Muzan and Kokushibo.
But, when it comes to who was the better Hashira, Tengen wins by a considerable margin. His experiences as a shinobi and as a Demon Slayer far exceeded Rengoku's, and led to him developing far superior strength, battle tactics, and techniques.
He would be disoriented by the shockwaves created by Akaza's blows. Tengen has anti-demon bombs that can disorient them for a short period of time, but this wouldn't be an effective strategy when Akaza uses Compass Needle, which allows him to accurately pinpoint and aim for his opponent's weak spots.
Despite being the lowest of the Upper Ranks, Gyutaro showed much of his demonic prowess by making Tengen lose his left arm and his left eye in battle. However, Giyu would have been a better opponent for the demon and could have defeated him without losing any limbs.
5/14 Fastest Hashira In Running
Despite his large and muscular build, Tengen Uzui is the fastest runner among the Hashira.
Mitsuri. The love Hashira and upcoming featured character of season 3, Mitsuri is best known for her extreme affection for everyone in the Demon Slayer Corps.
1) Shinobu Kocho
The Insect Pillar of Demon Slayer Corps, Shinobu is undeniably the smartest individual. She might not be physically stronger than others, but her intelligence is what kept her going.
2) Tengen Uzui
Given his performance against Gyutaro and Daki, there is no way he'll be able to beat Obanai Iguro who also happened to activate his Demon Slayer Mark.
Without a doubt, the flamboyant Tengen Uzui is physically the fastest Hashira in the Demon Slayer Corps. His sound breathing technique is a derivative of thunder breathing, one of the quickest breathing styles. He was fast enough to keep up with Daki without any difficulty.
Nezuko setting Tengen on fire. By the end of the battle, Gyutaro's poison has spread throughout Tengen's body resulting in his inability to speak. As he lays dying from the poison, Nezuko Kamado intervenes and uses her her Blood Demon Art to burn the poison out of his system, allowing him to rejoice with his wives.
But, when it comes to who was the better Hashira, Tengen wins by a considerable margin. His experiences as a shinobi and as a Demon Slayer far exceeded Rengoku's, and led to him developing far superior strength, battle tactics, and techniques.
Muichiro can defeat Akaza easily with his petite body that leverages his speed. Moreover, his ability of Transparent World can aid him in landing a fatal blow on Akaza's weak spot.
During his battle with Gyutaro, Tengen used his muscles to stop his heart to temporarily prevent the poison from circulating, which let him get the drop on Gyutaro who believed he was dead.
3 Hashiras that can beat Rengoku in Demon Slayer
Gyomei is considered to be the strongest Hashira in the series. His contribution was monumental in the battle against Kokushibo and Muzan.
DakiTan is the ship between Daki and Tanjiro Kamado.
Physically Tengen Uzui is faster and stronger but when it comes to willpower Kyojuro Rengoku is likely a bit more stronger from what I've seen, now based off feats Kyojuro might scale slightly higher than Tengen because he was fighting against Akaza almost until daylight and while Akaza might of been not serious and ...
Giyu Tomioka and Sanemi Shinazugawa attend as the final surviving members of the Hashira, and together they they get a confirmation that not only are the demons all eradicated, but that the Demon Slayer Corps will be disbanding.
As it turns out, Tanjiro has received a few promotions during his service. However, saying that Tanjiro has become a Kanoe doesn't mean much on its own. The Corps' ranks and functions are fairly straightforward.