Excalibur. Famous beyond legend and lore, it was most likely a steel Roman spatha, which would cut cruder bronze swords like butter.
Claiomh Solais, the shining sword of Ireland. Found in many ancient stories, and even commemorated on a stamp.
Fragarach is the sword of the ancient Celtic God Mannanan Mac Lir. With a name meaning “Retaliator” or “The Answerer”, it was THE sword of Celtic myth.
Shamshir-e Zomorrodnegar was a pre-Islamic Persian blade, in the story of Amir Arsalan. It was a charm against magic, and wounds it inflicted were particularly hard to heal.
Tizona was the sword of El Cid. The greatest legendary hero of Spain, it saw him through countless battles.
Now your characters can forge their own legends, wielding these mighty ancient blades of lore!