Just about calling it done on the chestplate after attaching the backpack straps. I might add another detail to the underarms on the sides but this is about done.
Don't be trying to steal my Southern Guys Sean!
Throw a little bit of legitimate dirt on the straps, and that will help add to the weathered effect.
Or maybe he's a true ODST and he keeps his equipment clean and in good working order!
EDIT: really is fantastic looking, though. Very good work!