Hi Ian. I had similar thoughts on the decorative motifs.
If it's not copper, the blade must be a very high-copper content alloy. In some areas, the metal has a shiny, red appearance. It seems like it's holding a nice edge, but it must be fairly soft as the very distal 0.3 cm of the tip is folded over on itself. It's pretty substantial, enough so that I'd be suprised if this was a purely ceremonial weapon. (Although the extreme rarity of useable copper-bladed weapons in general doesn't really support this.
).
I'll try to get some close-ups posted. The auction photos aren't great.