[Nikelaos]

I always thought the turning blue was the unit freezing and that it had a random chance like being set on fire with a heat aura. Though I believe freezing only causes fatigue as opposed to the damage caused by fire.

So that would partly explain why he gained more fatigue from a cold aura unit. Also bear in mind that a neifel Jarl might have a cold aura stronger than the heat aura of several abysians. Were the heat/cold auras of the units your olm fought equal? Were there more cold units than heat units?