EverKira
Recruit
Leadership is such a nigh impossible thing to level without calling armies forever. Recruiting troops is currently the only way early game to level leadership. Leadership will also level up if you get your morale to over 75 for a prolonged period but getting this high for very long is very difficult. I think that leveling troops up should also give leadership XP. 5 points from tier 1 to 2, 10 points from 2 to 3, 15 from 3 to 4, 20 from 4 to 5, and 25 from 5 to 6. It gives a bit more leadership without completely overpowering it to get access to the leadership perks by keeping your troops alive and getting them stronger compared to right now where just recruiting then releasing and recruiting again would be the more efficient way to level up the skill.