Strap width decides comfort
All the weight of a messenger rides on one shoulder. A narrow strap concentrates that load into a line; a wide, padded strap spreads it. Past about eight pounds, no strap makes a single-shoulder bag comfortable for a long walk.
How leather ages here
The flap creases where it folds, and the strap darkens where your hand rests. On full grain, this becomes patina. On coated leather, it becomes a shiny line. Neither is a defect, but only one improves with time.
What to check
Stitching at the strap anchors, a closure that works one-handed, and whether the flap actually covers the opening in rain rather than stopping short of it.
