Wait, so the cannister contained Torrin's head and a bomb? Then why did Ardon spend all that time arguing with the Nightmare Spirit about whether or not to keep him alive? I'm missing something obvious again, aren't I?
Ardon did that after we last saw him (and after the argument. The Nightmare spirit was laughing because it had won the argument). That is presumably why he told Manuel to get over there, he had to set up the bomb carefully and Manuel had shown he was good with devices. While Manuel was doing that, he presumably executed his brother and chopped off the head.