Will Welch, the 41-year-old editor of GQ, towered over the other pedestrians as he walked along Church Street in Lower Manhattan on the first night of New York Fashion Week. He was dressed in a blue suit that had been custom-made for him by Ermanno Lazzarin, the proprietor of Eral 55, a men’s shop in Milan that GQ recently named one of the world’s 100 best clothing stores. Mr. Welch said he liked the fact that bespoke suits are never quite perfect: “All the fabric is cut by hand, so the pockets are always irregular.”