Anyway, 4500 years ago is before anyone speaking anything resembling Greek was in Greece. It would be the so-called Early Helladic Period--the Greek-speakers are thought to have invaded Greece about the end of that period (somewhere in the vicinity of 2000 B.C.). Depending on where Mesi is, it could be an area which didn't have a Greek-speaking population until later (first millennium B.C.).
I think “mesi” is the root for “middle” or “center”. If that’s the case there might be several of them scattered around Greece. I seem to remember reading something in Herodotus where he’s bad mouthing Thracians and mentions Mesi.
Mesi is a villiage located in the Nomos Imathia in Northern Greece:
Here's a picture of the weapons: