The urumi (curling blade) is a long sword made of flexible steel, sharp enough to cut into flesh, but flexible enough to be rolled into a tight coil. Originating in South India with name of Surul Pattai (Tamil: ?????? ????????????), it was most popular in the North Malabar Coast of Kerala and is often mentioned in the ballads of the region.
http://en.wikipedia.org/wiki/Urumi