I emailed a friend of mine who took a Master's in Classics at Yale and asked him about the phrase "gladius hispaniensis". This is what he had to say.
"Spanish sword" is right. "Ensis" is indeed an alternative word for sword -- a synonym for "gladius," according to Quintilian, and almost completely restricted to poetical use -- but in your example it's an unrelated gentile suffix [it designates national origin -- from gens, gentis, "people" or "nation". Just a term found in old grammar books], meaning "of" or "belonging to." So hispaniensis, derived from the noun Hispania, is simply an adj. meaning "Spanish." Other examples are germanicensis ("German") and siciliensis ("Sicilian"). The Linnaean botanical nomenclature contains many such species names: "canadensis," "caroliniensis," and even "noveboracensis" (discovered in New York).
Remembering exactly what sort of sword a gladius was is your specialty, not mine. Presumably it's what a gladiator used: something straight and short, capable of both cutting and thrusting. In literary use it's a general word for sword."
Matt, thanks for educating me about the Latin word "ensis" for sword, and you're right about Spanish in modern times not referring to the whole of the Iberian peninsula, but I guess I don't agree with the Spanish appropriating that term for themselves to the exclusion of the Portuguese in the first place, and I certainly don't like calling the Castilian language Spanish!!!
About Etruscan: it is not considered an Indo-European language but an isolate though it seems to share many words with other languages. In fact, Latin borrowed considerably form the Etruscan culture though I don't know if that included martial matters. Here is an interesting website to the Etruscans for those who are interested:
http://www.mysteriousetruscans.com/ Matthew Webb
Oklahoma City, OK
USA