Shiryu swordsmanship is rainstorm, shiryu either feed his sword a thunderstorm devil fruit or he can generate ilusory rain with lightning made of haki coming out of raiu. Now after my research Im even more convinced shiryu have lightning based swordstyle plus nothingless with clear clear fruit awakening.
It’s like we are back to shanks and Kid. People think Oda doesn’t love these old characters and doesn’t want to give them hype