Oda is clearly playing a game with their nicknames here. After Gold > Silver > Copper, now we have Golden Lion > Silver Axe. It also probably indicates that Shiki was probably a bit stronger than Silver Axe in their rivalry
Maybe they were Rayleigh and Gaban opponents in GV. We're starting to get where their legendary status come from
Roger though: Please Garp, help me fight this guy(Xebec) who kicked my ass a year ago. I can't do this without you