ROME — Carmine Mainella’s calling card is his call. “Arrotino, arrotino,” he shouted on a warm September morning, strolling with an easy gait on a sidewalk in central Rome, announcing his trade: a sharpener of knives, scissors, meat-slicing blades and sundry metal items that have lost their edge.

He need not even yell. Mr. Mainella, who turns 75 on Oct. 20, has been making pretty much the same rounds for decades. “People expect me,” he said. “As long as I’m still circulating, they know where and when to find me.” He works with a motorized stone wheel that emits a deep growl under the canopy of a mini-truck he customized decades ago to accommodate his loss of a hand to a firecracker when he was 14. (One client whispered that he had cut off his own hand because of an unrequited love, a theory that made Mr. Mainella laugh.)

“All of Rome knows him, after all these years,” said Franca De Zuliani, the owner of the Ristorante Papa Rex, a restaurant not far from the Vatican and one of Mr. Mainella’s bimonthly stops. “He gets all over the place.”

Mr. Mainella is one of the last of a dying profession. Much of his old client base — corner butcher shops, delicatessens, mom-and-pop groceries — has been swallowed up by supermarket chains. Other clients in downtown neighborhoods here have capitulated to souvenir shops, victims of high rents and modern shopping habits.