Two groups of men stood on opposite rooftops perched on a hillside overlooking Rio de Janeiro’s Ipanema beach, taunting one another. It was a macho showdown between opponents wielding unlikely weapons — kites.

On this July morning in the impoverished neighborhood, they were using taut, sharp-edged kite lines — known as “cerol” in Portuguese — to slash their opponents’ lines, ripping their kites from the sky.

Kite fighting has caused horrific injuries and even deaths, and a bill moving through Brazil’s Congress is seeking to prohibit the manufacture, sale and use of the razor-sharp lines nationwide, with violators facing one to three years in prison and a hefty fine.

Sounds like this is more than ordinary kites.

My in-laws are keen kite flyers and travel around the country to kite festivals. As soon as someone sets up an Indian fighting kite stall, the serious flyers pack up and go home. No-one’s going to spend thousands of dollars on materials just to let some 12-year old with a $10 kite cut their lines.

My dad told me stories about kite fighting and showed me how to use glue and glass on the string to make a knife that would cut the other line. It’s not a sport that’s directly harmful unless you try to grab the string.