The Sacred Jewel, or Shikon No Tama, is the powerful jewel that many demons seek. It is said that this jewel grants the desires of the beholder. 50 years ago the priestess, Kikyo, protected the Sacred Jewel from any demons that were after it. Inuyasha was once after it 50 years ago in hopes that using the jewel would make him a full demon. However, Kikyo pinned him to a tree before he could get away. Before Kikyo the jewel was protected by the priestess Midoriko but she died protecting the jewel. In previous times the jewel was accedintally shattered by Kagome's arrow. The Inuyasha gang now hunts for the pieces and hope to restore the jewel soon.
Tetsusaiga is Inuyasha's powerful sword. It was made for him from a fang of his father. Tetsusaiga has many powerful moves but its most powerful attack is the Backlash Wave. When Inuyasha is a human the Tetsusaiga can not transform but is still usable for defense and some attacking. The counterpart of the Tetsusaiga is Sesshomaru's sword, the Tenseiga. When Inuyasha's father made the two swords for his sons he made it so the the swords could never be used against each other so his sons wouldn't try to kill each other.
This staff belongs to Jaken, the annoying little toad demon that always follows Sesshomaru around. This staff has 2 heads carved on it, one of an old man and the other of a young lady. The heads are capable of attacking with shooting fire however Jaken rarely attacks at all.
The Tenseiga is the sword left to Sesshomaru by his father. However, unlike the Tetsusaiga, Tenseiga heals and revives people rather than kill them. Sesshomaru hates this sword cause all he wants to do is kill Inuyasha. Sesshomaru has used this sword only once and that was when he revived Rin after she was killed by wolf-demons. Now Tenseiga is rarely used at all but still sits there in its scabbard by Sesshomaru's side.
Banryu is the wickedly cool halbred that is always wielded by Bankotsu. This sword is very big and has a wide strike range (which makes it wickedly cool!). When The Band of Seven wear beheaded 10 years ago Banryu was taken by the Lord of the village where they were beheaded. When The Band of Seven were resurrected recently, Bankotsu went back to the same village and reclaimed his "Companion" as they call it. When Banryu got a power upgrade with Shikon Jewel Shards embedded in it to fix it up after it got cracked by Tetsusaiga; It really became a force to be reckoned with. Of course, powered by the shards or not, Banryu and Bankotsu still lost to Inuyasha.