First of all, sorry about any mistakes in the translation from Portuguese to English!
Picture of the ship (didn't send the img because it was too big):
Source: Poder naval | Read more: Incorporação do Navio-Patrulha Oceânico ‘Amazonas’ à Marinha do Brasil | Poder Naval - Marinha de Guerra, Tecnologia Militar Naval e Marinha Mercante
There's more information in the news but it would be too much for me to translate, sorry for that.
Those weapons could be more powerful, don't you think? Anyway, thoses vessels were to be sold to Trinindad and Tobago but they didn't buy it because of economical issues, and then Brazilian Navy took the oportunity and bought it.