But then again, those old guys are spartans..., its like letting mustang fight yoda here... The only time we see mustang try and attack with flames, he was stopped by a kick from an old guy.
Moral of the story: Dun underestimate the old man. For a full list of examples
http://tvtropes.org/pmwiki/pmwiki.ph....BadassGrandpa
EDIT: Anyone thought of Mr Gold Tooth as our fifth sacrifice? And the main reason why mustang was able to beat Envy and Lust: Becoz they are slower, with respect to Bradley and Sloth, which gives him just enough time to react and attack. We saw what happened when Envy tried to take the battle to close range. But if he cant react to the attacks of the old guys fast enough, i guess its safe to say he will have a very tough time against Bradley.