Every site I've found describes combat in FE Heroes to be Strength + Weapon Mt - Enemy's Defense(or resistance if magic attack). However in testing this I've found that the Weapon Mt is not included. For example:
Attacker: Strength 46, Weapon Mt 15
Defender: Resistance 25
Damage = 21
Shouldn't it be 36 damage if Weapon Mt is added? There were no skills or adjacency bonuses involved so that is not the reason. Am I missing some other factor?
Edit: It was a Green Tome user against another Green tome user.