Why did Sesshomaru keep Tenseiga in the first place?
In the beginning of the series, he clearly loathed the sword, deeming it useless, and hated that it was the sword his father left him instead not the Tessaiga. He didn't strike me as the "its better than nothing" kind of guy, so was it just out of respect for his father?
If the world chooses to become my enemy, I will fight like I always have