Maybe this name got also another history, probably in France, and from the region of GUASCOGNA. For this it was maybe Guasco, Guascone and means a guy full of himself.
Vasco da Gama (IPA: ['vaʃku dɐ 'gɐmɐ] (Sines or Vidigueira, Alentejo, Portugal, c. 1469 – December 24, 1524 in Kochi, India) was a Portuguese explorer, one of the most successful in the European Age of Discovery, and the first person to sail directly from Europe to India.
I love it! It seems like the quintessential Spanish explorer/conquistador's name. The only thing I don't like is that the V gets changed to something that sounds like a B in Spanish, but doesn't that get fixed with Italian pronunciation?