Hi Andrew,
Actually the cuphilt rapier had essentially given way to the smallsword in most of Europe and England by 1730, however the Spaniards, who remained formidable and extremely tradition swordsmen, still clung to thier cuphilts through the 18th century and even into the 19th.
While this example clearly is not of true cuphilt form, it is an interpretation of one.
One thing I would note at this point (no pun intended
is that the 18th century was a period of neoclassicism, revivalism and fashion obsession. There was the traditional mens obsession with dueling, and most certainly various schools of fence were wrought with members of the gentry honing thier skills for the fashionable possibility of the duel.
I think the single hope that this weapon might be a servicable weapon, although it does not seem to have age dating to 1730, may be that it could have been a revival type weapon intended for actual use in sort of a 'mens club' type atmosphere.
There were many of these underground exclusive type organizations, the secret society type with Freemasonry heading the fore. There was acute interest in cabbalism, numerology and many forms of occult practice. One such club that was notorious in England was known as the "hellfire club".
While this suggestion is admittedly 'wild speculation' on my part, and I would suggest that even during Victorian times, there was vivid revivalism that stirred romanticism along with the writing of Scott and others as well as the advent of the 'Gothic' form of novel. Perhaps this interesting piece was one of the type of weapons that became in demand, as illustrated by the work of Ernst Schmidt, even if it is not one of his actual pieces.
We may recall that the German practice of 'duelling' with 'schlagers' with the express intent of receiving battle scars was quite the rage well into the 20th century, in fact I am uncertain but may still be practiced.
Just some food for thought
All the best,
Jim