Sometimes, leather-aproned, hairs in his nose,
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This shows how the profession of a Blacksmith is not a glamorous job. It is not about looking good while being productive, rather it is only about making a useful object for someone else.
The “Sometimes” of this line shows that the job of a blacksmith is not always a suit and tie kind of job. There is no formality to this profession, and no required uniform. He has been doing this job for such a long time, that he has lost the urge to look or dress a certain way.
All of his customers have known him for a long time and know what all he does, so he has become comfortable with who he is and does not worry if there are “hairs in his nose.”
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