Banal and trite are close synonyms, but blasé is different: it refers to *a person's attitude* toward things. Being blasé means feeling indifferent toward something, usually something that other people react to. "He's blasé about these political speeches now. He has heard it all before."

I have no sure, but, i think that all words are just synonymous... By the etymology, 'Banal' and 'Blasé' are borrowing from French and 'trite' come from Latin. If you find out other information about this terms, let me know ;-)