Tetsusaiga is the sword used by the Hanyou, InuYasha, in the Anime show, "InuYasha". It was originally forged by Totosai, by orders of his
father, out of his
Father's fang. It was mean't to Protect InuYasha, but ever since it was broken, it is now up to InuYasha to protect himself, combining the two powers of him, and his
father, creating the now Bigger Tetsusaiga, which proves difficult to hold, because of its emence weight.
From what They find, In episode 7, "Tetsusaiga, the Phantom sword" It can only be used by a weilder with Kindess and mercey for humans, coming from his
father's love of Inuyasha's mother. Since Shesshomaru has no Mercy for Humans, the sword would no except him.