AI for this game is going to be tricky.
Humans can pull so much strategies out of their brains it is always hard for the AI to keep up. In this case the AI ignored the biggest threats and went for the sovereign. In other cases the AI could whack what is closest while getting hit from more dangerous spells by the sovereign or champion.
Maybe the AI isn't fully implemented yet. It clearly needs to prioritize its threats better. Realistically the bandit didn't have a chance. I am more worried about the AI on the strategic map. I hope they don't build dumb units, build cities in dumb places.
In my one test game the AI stacked units on a patch of unclaimed fertile land. I wondered if that was by design or purely coincidental.