Changing Sabin's Blitz moves?

You can change anything like that about the Blitzes using FF3usME. You probably won't be able to make Blizzard Fist in exactly the way you're thinking, because that animation is part of a battle event, but you can make something similar. You can make a new button combination, different properties for the attack, a more fitting animation (though like I said, not the same as Vargas', maybe more like the Blizzard spell or BaBaBreath animations), and possibly cause it to work like Sneeze (but fail on enemies immune to instant death) all using that tool.