Licht, the leader of the Eye of the Midnight Sun, said that each person in the Third Eye (which are the three strongest members of the Eye of the Midnight Sun (Fana the Hateful, Rhya the Disloyal, and Vetto the Despair)) are stronger than him, especially in battle.
So if they're all stronger than him, why is he the leader? It seems that they all trust him and are extremely loyal (hilarious, considering he employs Rhya the Disloyal, but I digress). It also seems like he maybe started the whole thing, or saved them somehow, so I guess that could explain it? I don't know though.