The Buccaneer Costume essentially resembles the costume worn in Honor Among Thieves, but with some minor adjustments; there is no peg leg, and there is no eyepatch. There is, however, a hand cannon that Sly can hold in his arms, and a saber for him to slash with.
"Prior to the completion of the Cooper Vault Job, Sly went to Blood Bath Bay to get Dimitri's diving gear. While there, he got a pirate disguise. However, thanks to Bentley, this costume has now been given a much needed update that now included a hand cannon and a saber. With the hand cannon, Sly can blow up obstructions and enemies, and with the saber, any ropes and chains that need cutting can now be cut."
By pressing the square button, Sly can use his saber to slash at enemies and slice ropes and chains in two. Pressing the circle button sheaths the saber and allows Sly to use his hand cannon, at which point Sly only needs to use the square button to fire the cannon. By pressing the R1 button, Sly can fire the hand cannon at targets above or below him.