[X] Mercy. His crimes do not deserve forgiveness, but this is not about 'deserve'. Spare his life, bend his knee, and give the man a chance to atone for his failures with loyal service in your name.
[X] Exile. You find this man unworthy, and banish him from your sight. Let him go forth and spread the word of what happened here today, the first of many heralds that you must send forth to better enact your will upon this world.
[X] Death. A million hands stand ready to enact your will, and the world you would create has no room in it for such treacherous monsters. Let him reap what he has sown, and die as he would have condemned others to die in his place.