In a game as LA Pythium I wanted to get rid of a Leo for whome I found no use (and the bastard was killing my dominion in the border areas), I put him at front with the troopers (slightly aside of them) in an army which was attacking an AI controlled nation. Scripted IIRC Fire Shield, Fireflies, Burning Hands x 3, Attack rear.
When I was viewing the battlereport, to my suprise he had dutifully burned quite a few enemies (those Leo's apparently can take a beating with just their standard equipment), but was killed when, after he had charged forwards and passed out, got surrounded and killed.
Didn't think of it more then except as a quirk, but now that it was mentioned, maybe a few Leos at front would indeed be nice flamethrowers together with for example fire drakes or some such?
Hmmm... have to test this out at some point
