Just as Hanzō finished off Chiki, the commander from Sunagakure Ninja Village, the troops led by Kagami Uchiha punched a hole through the Sunagakure Ninja Forces' defensive line. Through that opening, the Konoha forces drove deep like a sharp blade, pushing the Sunagakure Ninja Forces to the brink of collapse.
Although the power of Fire Release had been severely curtailed, the Uchiha Clan excelled at Shurikenjutsu and other forms of Taijutsu as well. As a Jonin of the village, Kagami Uchiha had also mastered other chakra nature transformations. With the legendary Sage Tool, the Gunbai, in his hands, his achievements in battle were no less impressive than Hanzō's.
Kazemori Masaki believed that, although Kagami Uchiha lacked the Mangekyō Sharingan, his wealth of combat experience and ninjutsu, together with a Sage Tool like the Gunbai, meant his strength might not fall far short of Sasuke Uchiha's at the time of the Five Kage Summit.
As Black Zetsu had said, the Sharingan was essentially a weapon. The stronger the weapon, the greater the boost it gave its wielder. But if the wielder's own underlying strength was already high, even a relatively inferior weapon could demonstrate formidable power. Conversely, someone whose underlying strength was lacking could not become a powerhouse capable of standing on their own merely by possessing the Mangekyō Sharingan.
In the battle between the brothers Uchiha Itachi and Sasuke Uchiha, Kazemori Masaki believed that Itachi had indeed held back, but only in how he combined his abilities. If any one of Itachi's abilities were considered individually, Masaki believed he had used it at full power.
In other words, Kazemori Masaki believed that Sasuke Uchiha had genuinely broken Uchiha Itachi's Tsukuyomi with an ordinary Sharingan. Where Itachi had held back was in using Tsukuyomi alone, rather than following it up with