The TWO Swords: Tetsusaiga and Tenseiga
Tetsusaiga is the sword that InuYasha's father ordered Totousai to forge for InuYasha. It was said that the Tetsusaiga could slay 100 demons in one stroke (InuYasha taps into this power for the first time in Episode 28, Miroku Falls into a Dangerous Trap)
Totousai also explains about the sword that was forged for his brother Sesshomaru, the Tenseiga. The rumor of the Great Sword Tenseiga was that it could SAVE 100 lives with one sweep. Given to Sesshomaru it wasn’t used for the longest time (the heartless fiend). But I know for fact that he uses it to save a human child's life in one of the future episodes. So it seems that Sesshomaru can love. Who knew?
Another thing about the Swords was that they protect their owners and in battle are evenly matched. Like in this episode was it or the next, when InuYasha and Sesshomaru fight, whenever Sesshomaru tries to strike him he protects himself with the sword (its not like he can strike him with the Tenseiga anyways for it only heals) which it does by the way when InuYasha strikes Sesshomaru, sparing his life.
Hmmm, It's said that their father did this so they wouldn't kill eachother. Makes sense to me. Submitted by InuYasha Fan_Moonlight Shine