I don't have an answer on the bone handle or carvings. The Japanese would use a small blade simular in length, about 15 inches like the one you have to commit Hari Kari which also known as sepuku, one would take a wakizashi (short sword) and dissembowel oneself.
If there are no markings one the blade close at the tang, (closest to the handle), then it could be just an after market knock off.