Damage is not might
Two numbers that look interchangeable and are not. Getting them straight is the difference between a trade and a clean kill.
A unit dies when
it has at least 1 damage
and
damage ≥ its might
Remember
Damage is marked on a unit; might is what it takes to kill it. A unit dies only when it has at least 1 damage AND that damage is at least its might — so 0 might with nothing marked on it lives. And check for [Shield] before you count: a unit reduced to 0 still defends as a 1.