Crescent Rose was Commander Ruby Tachibana's modified DL-44 heavy blaster pistol that she used whenever she and Rose Squadron were given a ground operation that didn't require their X-wing starfighters. She modified it to be as heavy as it can be.
Sometimes those who encounter her would often mistake that Ruby stole Han Solo's blaster pistol which earned her a nickname "Solo Thief" amoung bounty hunters, smugglers, and pirates which multiple attempts, of those who heard the stories, were made on Ruby's life due to her blaster pistol.
Han Solo himself even heard of them and knew that it wasn't true as he always had his blaster by his side at all times.