Iudex Gundyr First Boss Down

I picked up the steam deck last night for the first time in a while and resumed the initial (secondary?) graveyard in Dark Souls 3. Last time, I'd died several times to this first boss, only once getting him as far as his second phase. This time, for reasons that are still unclear, I succeeded. I started with several rounds of this graveyard route, initially to see whether there were more fire…