<p>“The italian explorer, marco polo, is an epic ninja.”</p>
<p>Why is the above wrong. Why does it have to be: </p>
<p>“The italian explorer marco polo is an epic ninja.”</p>
<p>Also is there a difference between usage of “more often” and “more frequently”?</p>
<p>The phrase Macro Polo is a restrictive appositive and thus should not be set off by commas. Saying Marco Polo is restrictive because it is necessary for the sentence to keep the same meaning. For example, “My sister Sue will be having a party next week.” (Sue is essential to the meaning of this sentence because it tells which sister is having a party.) It wouldn’t be, “My sister, Sue, will be having a party next week.” </p>
<p>You could, however, reverse the ordering of the sentence to keep the comma. "Marco Polo, the Italian explorer, is an epic ninja. (But you can only do this because “the Italian explorer” is not restrictive, it only adds to the description of Marco Polo.)</p>
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<p>It would be if you had only one sister because the apposition would then be non-restrictive. By the same logic, “Marco Polo” should not be offset by commas in the original sentence because there is more than one Italian explorer; if there were only one, commas would be used because there would then be no restriction by the appositive phrase.</p>
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<p>No.</p>