"Iron blinds a sharp knife."
However, this is a proverb with a deeper meaning. The English equivalent would be:
"Familiarity breeds contempt."
The proverb suggests that when we are too close to something, we may lose our ability to see its dangers or appreciate its value. Just as a sharp knife may go unnoticed when it's constantly in our hands, we can become blind to the potential harm or beauty of things that are too familiar.