It is a fairly well established part of dogma that trolls regenerate.  It’s also established that fire inhibits this ability.  For the people who didn’t know that, that’s why Lisa was set on fire.  As for the other girl, well, if you know who she is, you know that Lisa considers most of her actions foolery.

I’ve mentioned that Lisa as a character went through a few iterations before becoming the knight-priest of war.  One of those was actually as a gladiator an instrument of “panem et circenses.”  In her official biography, she spent a year or so fighting in gladiatorial games.  She actually wasn’t very good at it.  Gladiators are as much about the celebrity and show of the match as they are about ability to win a fight.  Lisa is more about personally overwhelming and destroying her foes.

She’s a bit like one of my favorite scenes in Stargate SG1.  The team brings weapons to supply a band of rebel Jaffa.  When the rebels are disappointed that the humans brought rifles (technically carbines) and pistols instead of staff weapons, Jack holds an impromptu shooting contest, with the Jaffas’ best marksman armed with a staff weapon and Major Carter firing a P-90.

After humiliating the staff weapon’s performance he holds one up and declares, “This is a weapon of terror.  It’s made to intimidate your enemy.”  He then holds up a P-90, shouting, “this is a weapon of war.  It’s made to kill your enemy.”