Here's what "bilbo" means -
: a long bar of iron with sliding shackles used to confine the feet of prisoners especially on shipboard.
Merriam Webster provides a vague history and etymology for "bilbo" -
History and Etymology for bilbo
perhaps from Bilboa, Spain
Bilboa, Bilbao, Spain
kind of sword esteemed for temper and elasticity, 1590s, from Bilbao (in English Bilboa), town in northern Spain where swords were made. The town name is Roman Bellum Vadum "beautiful ford" (over the Nervion River).
and Lexico states that it comes from -
mid 16th century: of unknown origin.
for its first meaning.
Therefore, I would like to know more about the history and etymology of the word "bilbo", and how its first meaning came into use.