Спарвьеро никогда не назывался swordfish.
Swordfish - название международного проекта создания кораблей этого типа.
Admiral Elmo Zumwalt began the PHM project to increase the Navy's number of surface vessels in a cost-effective manner. The project, called Swordfish, was to involve four other navies—the Royal Navy, Canadian Forces, the Bundesmarine, and the Marina Militare, for as many as 100 craft.
Uk, Canada and Germany retired from the project, while Italy and USA continued and at the end of the seventies the new craft was in service, 6 Pegasus hydrofoils in USA and 7 Sparviero in Italy, similar design and similar weapons but the american one was a bit bigger (40 meters VS 25 meters)
The US Navy retired the Pegasus class in 1993 and the Italian navy Sparviero in late nineties due to high operational costs (comparable to a frigate).
They were armed with a 76mm gun and anti ship missiles.
Japan bought 3 modified Sparviero in early nineties, but they were retired few years later.
There crafts were the "jets" of the sea, with their outstainding speed (50 knots!!) and their tipical noise similar to a fighter jet when flying on the sea surface.