Purple noble, yeah. My last look at the name meaning seemed to suggest that fidalgo was more or less a genderless term and only used a male ending because there wasn't a neutral one and most of those it would describe (at the time it was coined) were male. Which would make sense, given how many languages use male pronouns as collective or gender neutral ones.
My sources also seemed to suggest that there were other words for specific forms of noble and that "fidalgo" had mildly derogatory connotations, implying someone born into wealth with little sense of its value.
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I cannot be sure, however, since I'm not well enough acquainted with the language to know the nuance for myself and it's entirely possible that one or both of the above are just the translators' own viewpoints being projected through their work.