Hmm, i think Wa No is better suited, though it does not rule out GreenBit having one of course but 2 consecutive Poneglyphs could be a bit too much
Consecutive? Did you forget that they had been to Punk Hazard before Dressrosa? Also, don't forget that Poneglyphs are scattered all over the world. Fishman Island is located at the bottom of the Red Line, while Greenbitt is deep into the New World, they skipped some islands along the way to reach Punk Hazard you know.
I don't know if it was mentioned around here, but someone at NF mentioned a possible link between CP0 and the Ancient Weapons (or even Uranus itself). Their names comes from Aegis, which is the shield used by Zeus in the greek mythology. Zeus was speculated at first to be the name of the third Ancient Weapon, however as you already know, Oda surprised us all when he named it after the Titan Uranus (Zeus' grandfather) instead. As far as I know, while Oda does take alot of inspiration from mediterranean countries, "Aegis" is the only mythology-inspired so far.