The stick shown in the illustration is hardly a heavy and unbalanced item.

Nonetheless, this is getting pointless. The man is wearing trews. Gentlemen wore trews. They usually wore trews when riding. They carried sticks. Maybe Colquhoun rode to his destination, dismounted, and decided to take a walk. Perhaps a retainer ran along beside his pony carrying his stick, or else he carried it himself. It doesn't really matter, does it? The fact still remains that gentlemen wore trews because they often rode.