I can share my strength and courage with others. The larger the group, the better the effect.
Say you and I were fighting some enemy and we were surrounded, I could give you a power boost of sorts so you could keep fighting even if you were injured or exhausted. Now, imagine me using that on the legion of 200 I commanded at home. Effective, but I feel it's almost like me controlling them. Especially since I can help focus people on the objective.
There's also a side effect - I feel whatever emotions the people are feeling.
It's not something I like to do without permission. Even if the benefits are good.