Based on his personality traits and the scenario you've described, it's possible that he upgraded his look, including wearing the silver chain, to impress you or to show off his confidence. People often make changes to their appearance when they want to attract attention or signal interest in someone. His assertive and confident nature suggests that he may feel comfortable expressing himself through his appearance.
However, given his rude and confrontational behavior, it might also be possible that he just enjoys dressing up for himself or as a part of his personal style, rather than for anyone else. Some people with strong personalities can be a bit self-centered in this regard.
Consider how he interacts with you when he’s wearing the chain. If he seems more engaged or responsive, that might indicate that he’s indeed making an effort to impress you. Ultimately, the best way to gauge his intentions is through his behavior and communication with you.