"Arcos" means arc, or arch is essence, (ie. like a bow (same general idea)). Of course, "arch" can mean leader (as in "arch-druid"), but I wasn't joking about "bow-headed"
well, OK, "bow" is usually something like "toxou" in greek (mounted archers were the toxotes), but the point still holds...
really, though, linking the "arcos" to the "arch of the sky" or some such is probably a good bet; thus mixing it up semantically w/ Apollo/Apollonian...