So I’ve got some good news and some bad news. We’ll go bad news first.
Bad News: I’ve found absolutely no information about this specific cross.
Good News: My friend got back with me and I know the location of the cross. The cross is located at Le phare le la Garoupe (The Garoupe Lighthouse) in Cap d'Antibes.
But wait, there’s more. I did a little research on Pentagrams and Christianity. Apparently, early Christians used the pentagram for a variety of things.
There are many connections between the pentagram and Christianity. Before the cross, it was a preferred emblem to adorn the jewelry and amulets of early Christians (followed by an 'x' or a phoenix). The pentagram was associated with the five wounds of Christ, and because it could be drawn in one continuous movement of the pen, the Alpha and the Omega as one.
So I guess I was wrong in thinking pentagrams on a cross was weird.
As always, if you have any information on this, I’d love to hear more.