I played the original when I was like 12, and made Ramza a monk/ninja then just because I (correctly) thought monks and ninjas were cool. It steamrolled the whole game.
Another good trick on that fight is to use Ramza's ability that increases his speed over and over again in the first phase while just kiting Wiegraf around before his transformation. Do it for like 10 rounds and you'll be getting multiple turns for every one of Wiegraf's. The second phase is considered the same fight, so the buff persists. When the demon shows up, you can just pummel him to death before he even moves.