Μετάφραση - Πορτογαλικά-Λατινικά - Sou filho de Deus e nasci para vencer.

"Filius Dei sum et ad vincendum natus sum".

I'm afraid we can't omit the first "sum" in this case ...

"natus sum" - grammaticaly two words, but they do not exist separated in "perfectum", that is why "sum" here can't be considered as a common verb for both parts of the sentence.

Latin is known for being a laconic language, but in this case the sentence seems to me quite prolix.

Yes, indeed. The language is usually very laconic in its structure, but not always... Sometimes modern languages are simpler in their grammar.

You are very good at Latin, goncin! IMO you need only some time to come back to it...