Kay Vess is depicted wearing blue trousers adorned with Corellian bloodstripes.
Corellian bloodstripes were essentially a design element, taking the form of horizontal red or gold stripes, that could be added to pants, positioned vertically down each leg.
Han Solo possessed a pair of trousers featuring gold Corellian bloodstripes around 10 BBY. He wore them during the Coaxium heist from the planet Kessel. Han continued sporting pants with these bloodstripes, even during a ceremony where the Alliance to Restore the Republic awarded him a medal.
In 3 ABY, Kay Vess, the scoundrel, discovered some blue pants inside a container on the Trailblazer. This EML-850 light freighter had been pilfered from Sliro Barsha's Westhill Palace located in Canto Bight.
The first visual appearance of Corellian bloodstripes, though not specifically named, was on Han Solo's trousers in the 1977 movie, Star Wars: Episode IV A New Hope. Their official identification within canon happened with the "Kessel runner pants" cosmetic, a perk exclusive to the Ultimate Edition of the 2024 video game, Star Wars Outlaws.
Within the Star Wars Legends stories, bloodstripes signified a Corellian military honor bestowed for exceptional bravery. Gold denoted a first-class award, while red indicated a second-class award.