How pure is "nearly pure"? Modern bronze is 88% copper, 12% tin, which is arguably nearly pure copper. I'd guess that this sword is bronze (or maybe brass) as actually pure copper is pretty soft. At approximately the same time frame, copper was being alloyed with tin around the Mediterranean and there were trade routes for shipping tin, which was harder to find than copper.

As someone interested in kitchen knives, I found myself wondering what kind of edge would be best for bronze. Found someone who’d cast their own bronze (copper/tin) knives. IMO worth a read, in spite of it not going into edge angle or straight vs convex — but it did mention 88/12 bronze, once work hardened (repeatedly deformed/reformed) to have a hardness similar to mild steel — and hand sharpening on a stone produces a convex edge naturally, just because of the way we humans are hinged and the motions involved in sharpening.