Nigeria could be seen as a blessing to the continent Africa because she played a crucial roll in the formation of ECOWAS, she also supplies electricity to some countries in Africa and also have the highest population. In terms of security she fathered so many peace keeping nation to ensures the continent enjoys peace and stability. Nigeria is in did a blessing to Africa.
That blessing you are mentioning that Nigeria is to Africa, I as a Nigerian I've not seen it. Nigeria should first be a blessing to itself first before wanting to be a blessing to other African countries across the Sahara. This issue of Nigeria supplying another African country electricity is another mirage i find very difficult to believe why because, Nigeria itself doesn't generate enough electricity to supply her citizens because the national power grid collapse every now and then, so how do i believe such kind of story that nigeria supplies another country electricity.
What Nigeria can easily boost off is their numerical strength, which is the largest in Africa, outside that I don't see anywhere their pride is coming from. If you look towards the economic aspect, south Africa has a more sustainable economy than Nigeria in terms of GDP per capita.
The ECOWAS you mentioned is just a council of west African states, so it doesn't encompass the entire Africa and all the members of the council do supply military assistance to a country that is at war for of peace keeping.