Each yokai that Inuyasha faces sets a new standard of strength for the anime, growing more evil by the episode. The scale of power never bothers the half-demon, who uses them as training practice for his weapon, Tessaiga. Though each demon seems more powerful than the last, Inuyasha proves that sometimes all it takes to win is the might of a trusty sword.
This article contains spoilers for Inuyasha and Inuyasha: The Final Act.
There's a reason why Toga leaves Tessaiga for Inuyasha. Tessaiga is the Iron-Crushing Fang taken from Toga's own mouth, gifted to the half-demon, not for his demonic strength, but his undeniable humanity. Although Inuyasha is a half-demon and technically weaker than Sesshomaru, even his brother cannot deny the power of his sword.
And it's not just Tessaiga that makes Inuyasha strong. He has the strength to become a raging full demon and the humanity to save many lives when needed. With his determination to stay strong, Inuyasha becomes the hero that everyone needs.