You are right to doubt – it doesn't work on all units; Inspiration doesn't affect the entire army.

Is it technically possible to make it work for all units? Otherwise, it loses its meaning. But if that's not feasible, we can consider these options:

1) Retribution
(increases the damage dealt by creatures by 5% for each point of positive morale, but no more than 25%)


2) Empathy
(each time a creature of the hero triggers positive morale, the hero moves forward on the ATB scale by 0.10. If negative morale is triggered, it moves back by 0.10)


3) Preparation
(after placing a stack in defense, it strikes first in each attack against it, even if the attacking creature has the "No Resistance" ability. In addition, if the defending stack has the "Endless Retaliation" ability, it deals two blows: one before the attacker's blow, and the second - after)