Well, that's a typical question of nomenclature. Without a standard, each community ends up developing its own terminology.
So, to the question "what is a Bilbo?", the answer would be "Well, it depends who you ask", as it's already being seen here
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The sword posted by Fernando wouldn't never be classified as a "Bilbo" by a knowledgeable Spanish collector (nor as "colonial", either, by the way). In Spain this kind of swords, which are indeed considered as belonging to the same "family" as the ones posted by Manuel (Celtan), are known, generically, as "Tazas a la Portuguesa", or "Portuguese cup-hilts", with a chronology that, as Fernando said, spans from the end of the 17th c. to the beginning of the 19th, featuring a wide variety of blades -usually quite sturdy cutters-, many of them with German marks and inscriptions in Portuguese or related to Portuguese subjects. Distinctive -read "usual", you know how this goes- features are the thick, solid cups, frequently featuring the "rompepuntas" or "point-breaker", short sturdy quilllions with pear-shaped finials and frequently soldered to the cup itself, lack of inner finger-rings ("pas d'ane" you call them), and the pear-shaped pommel, usually faceted, and with the knuckle-guard attached to it with a screw.
The grip is usually of bare wood, barrel-shaped and with horizontal decorative carved lines (that one in in Manuel's first pictures would be an archetypical example), but I've seen many variations. I don't think the brass one in Fernando's exemplar is out of place in any way.
In Spain, the label "Bilbo" for swords is taken as a loan word from Anglo-saxon collectors and referred normally to swords with hilts featuring bilobulated shells, be them 17th c. rapiers or 18th c. Spanish Cavalry Swords. You may find them in dealer's descriptions meant for international audiences, in fact, but the term is kind of catching in the collectors community.
As I said, all of this is not about anyone being right or wrong, but about how sometimes things we give for granted may not be so when dealing with the international community. You wouldn't believe the amount of discussions I have had about what can be considered a rapier and what not, which invariably end up dealing with what *each of us* feels comfortable calling a rapier...
