From my recollection of history, the Council of Nicea was designed to bring all the Christian movements under one roof--as it was splintering into many different sects. Constantine (or his wife) was instrumental to bring all the leaders together to, as you say, "duke it out." The side that won had the mandate to eradicate the other side.

The god-nature of Jesus was established with this Council. Certain Christian writings were banned. As well, the tiered democratic elections of many sects was replaced by a top-down model, similar to the Roman Empire.

Basically the Council was more about who was in control of Christianity than about theology or bettering the human condition.