If it's a megalithic culture of S. India it's pretty old. Crucible steel production is known in early on S. India and Sri Lanka. Just not in the manufacturing of something like a sword however, until now.
Recently they found a iron dagger, riveted copper hilt as well. With sheets of metal riveted together to form the hilt.
The first one is a recently found copper hilt with rivets. The rest are from an early dagger found dating 6th century BC without rivets, but similar hilt design.
The hilt design is old as seen from the 2nd-1st Century BC warriors. I havent seen the hilt design again after 1st Century AD+, at least not in India.