Maybe Hiro was a little overzealous with the fire (he did want to give a good show), but he did his best not make the area of effect TOO large to actually injure any spectators. He didn't want to burn down the whole place, or kill anyone not involved in the battle. Hiro moved fast for someone in full armor, the armor was designed to be light, despite providing superior strength and defense. It allowed him to cut loose and move as he wanted.
Hiro took out the two minions, and he had the main vampire in his sights. He charged ahead at him, striking him with his sword, taking off his other arm. The vampire hit the ground, The vampire tried to get up, but Hiro stood with one leg on the vampire, preventing him from going anywhere. It was at this point, Hiro heard the chants of the crowd to finish off his opponent. To finish the vampire off. Hiro looked about the arena, watching the bloodthirsty crowd chanting. The woman running the Furnace spoke. He was one move away from earning the freedom of the Hunter's family.
If only he had more time, maybe grill the vampire for info about this woman, what kind of leverage she had on the vampire to keep him in line. But with an entire crowd of people watching, including this kingpin of the Furnace, he did not have that luxury. Not to mention, he had to secure the family's safety. They took priority. He looked down at the vampire, frothing at the mouth with blood, practically. He raised the sword above his head, blade pointed downward.
"Last words, Vampire. Tell me, before I kill you, why would you fight for this woman, to fight for this crowd's entertainment. Surely a vampire like yourself has better things to do than play gladiator. It'd be safer to hide in the shadows and pick off easier meals, than . . . this," Hiro whispered, just loud enough so the vampire could hear him. He waited for an answer, whether it was the answer to his question, or if the vampire told him to go screw himself, or some other sort of response. After waiting for a response, Hiro plunged the sword down into the vampire's chest, aiming for the heart. "You are avenged, Sir Hunter. Have some solace in the afterlife that your family will live on safely." With that, Hiro raised his fist in the air to hear the crowd's cheers.