The archaeologists said the weapons were believed to have been used during the Bar Kokhba revolt of Jews against the Romans in the second century.
“It's a very unique and important discovery, which is unprecedented in Israel,” Eitan Klein, director of the Israel Antiquities Authority, said at an event to unveil the find.
“We suppose that Jewish rebels took the weapons as booty from Roman units or they were collected in the battlefield and they were hidden in a cave as a cache of swords to be used or reused in future battles.”
The weapons were found in June, deeply wedged behind a wall of stalactites and preserved in wood and leather scabbards.
Without specifying the location over concerns about looting, Mr Klein said the discovery was made on Israeli territory in an area close to the Ein Gedi natural reserve.
“We are just beginning to understand what these could be,” said Guy Stiebel, a professor at Tel Aviv University who specialises in the Roman empire.
“It's not just about the Jews. It's about the Romans, it's about the whole Roman empire.”
Mr Stiebel said the weapons were well-preserved with their iron blades, sheaths and handles still intact.
“The fact that the climate is so arid and dry in the desert enables us every now and then to make such discoveries,” he said.
Archaeology is a highly political subject in Palestine and Israel. Some discoveries have been used to justify the territorial claims of each side.