Attack interval and debuffs from fatigue are very important pieces of information. But what their exact values are isn't mentioned anywhere in the game.
What exactly does fatigue do? What stats are affected and by how much?
And did you know that Empire Spearmen have an attack interval of 5.7 seconds but the version with Shields has an interval of 4.4 seconds? Most likely you didn't know because the game never tells you.
The attack interval could easily be displayed when you hover over Weapon Strength.
And the debuffs from fatigue could directly affect the unit's stats like all other abilities and spells do. Or the effect could be show as a small debuff icon on the unit card.
The same could be done for the buffs the AI gets on high battle difficulties.