In Fire Emblem: Thracia 776, every star gives a 3% bonus to hit and evade to all characters on the same map as their leader.
In Radiant Dawn, the tooltip for Leadership states that it determines the number of bond supports the leader can have, but this does not seem to be true, as even units with no leadership stars can have bonds. In reality, each leadership star the commander of an army has will boost the hit rate and evade of all units under his or her command by 5. However,all of the Leadership Stars in this game aside from Ike's are purely cosmetic.
|Affinity - Aid - Attack Speed - Constitution - Defense - HP - Leadership - Level - Luck - Magic - Maximum Hit Points - Movement - Movement Star - Pursuit Critical Coefficient - Relative Power - Resistance - Skill - Speed - Strength - Weapon Level - Weapon Rank - Weapon Skill - Weight|