One of his 3 main default outfits and this is the second one his Green Mercenary outfit... It may not looking like a mercenary like attire but its referring to a gun man of some sort.

Outfit Description
He wears a green scarf on his neck, green vest with mint green trims and accents, a green sweat band on his right arm, darkly colored greenish brown trousers, and pairs of grayish black boots, his trousers has a grayish black belt with a gray buckle and a matching ankle length green cloth hanging on his left hip.

Note
This was his outfit when He was sparring with his brother after reuniting with him and worn it as his normal civilian clothing.