What does Bertie arm himself with in Chapter 16? Where did he get the weapon from?

In Chapter 16, Bertie feels in danger of being beaten by Stilton. Bertie recalls a cosh, which he and Jeeves once confiscated off of his younger cousin, Thos. Bertie learns that Jeeves still has the weapon and goes back to London to retrieve it. Once Bertie is armed with the cosh, he feels much safer at Brinkley.