Hiraikotsu

Description
Hiraikotsu is Sango's gigantic boomerang and her primary weapon. Like the rest of the arms and armor of the people in her village, it was made from parts of vanquished demons. In Hiraikotsu's case, it was made from purified demon bones. Because of its supernatural material, it's nearly unbreakable and is a very powerful weapon. It appears to stronger than steel, while having the weight of wood. It was destroyed in chapter 485 but was repaired in chapter 488 imbued with a new type of power that acts like the backlash wave.

I Sango and Hiraikotsu
Sango uses Hiraikotsu in many different ways. The leather bands at either end allow her to grasp and handle it easily. At six feet in length and what must be fifty pounds or so, she handles Hiraikotsu very nimbly. Miroku states in the first movie that she must be very strong in order to be able to lift and carry it. Other than using it as a boomerang, she can swing it and wield it as a melee weapon. In fact she's killed countless demons like that as well as hitting Miroku over the head when he is acting around women. Hiraikotsu is also big enough for Sango to use it as a shield when the need arises, and the nature of its material makes it excellent for that purpose. When not in use, she uses a strap, possibly made of leather, anchored on either end by a buckle and using friction to hold the strap ends in place. She slings the strap over her right shoulder and the strap crosses down her body to below her left hip.

Sango has the basic knowledge and experience to repair Hiraikotsu; she likely was required to learn how to do so, as she sometimes went on exterminations alone. In the anime she had to return to her village to repair a large crack in the surface. The demon bones are worked as if the material was steel. A blacksmith's furnace is used to heat the weapon and bones until red-hot, and more bone is used to fill in the crack, repeatedly struck with a blacksmith's hammer. According to Sango's comments, it was likely her father that taught her how to do so. While she admits that her father's handywork would have been better, she was able to effect repairs of a quality that she was more than happy with.

Name

 * Hiraikotsu's name is made up of 3 kanji (飛来骨). A kanji is a form of japanese writing that each mean a different word by themselves, and can be combined to make new words; the first Kanji, pronounced with "Hi" in this case, means Flight or Flying. The second Kanji, pronounced "Rai" in this case, means to come or to return. Considering it's basically a giant Boomerang, the "Hirai" part is a way of saying in pure japanese that it is a weapon that flies back to you. Finally, the last Kanji, pronounced "Kotsu" in this case, means "Bone", referring to that it's made from the bones of demons, and thus is basically one big bone. The name itself has been interpreted many different ways, but considering it's kanji and function, the term "Flying Return Bone", or possibly "Bone-a-rang", is likely the most correct translation.

Trivia

 * As stated by Miroku in Affections Touching Across Time, the Hiraikotsu is much heavier that it looks but Sango makes it look light.
 * It is possible that the Hiraikotsu could be based from Ukyo's Giant Spatula from Ranma 1/2, which is another series made by Rumiko Takahashi. Not to mention that both users of each weapons are voiced by the same people.
 * In anime it was cut in half at least 2 times but in the following episodes it was showed togheter without explanation. But in the episode 56 it was damage and in the next episode it was said that it would need repairs.