About a year ago I found a sailor's cosh similar to this one in the Hudson River Valley, and just returned to the same dealer to purchase this one, which came from the same estate. From what I understand, this exquisitely crafted but brutal object was a sailor's weapon, preferred over the knife, and according to lore was carried by "Press Gangs," who would use them to gather a crew by rendering unsuspecting victims on shore unconscious, only to awake once out at sea. Housed inside the fine macrame/knot work at the large end is a lead weight, which would do the damage. The long stretch of the middle is stiff and strong but pliable, and there may once have been a wrist loop that attached to the very end of the handle. 

My research suggests that this fine example--referred to as a blackjack, or cosh, or sometimes "persuader"--likely dates to the early 19th century. 7 1/2” l x 1 1/4” widest diameter and in very good condition, with some surface wear, rich patina.