The entire reason Loki’s changed his getup (clothes, growing out his hair, even the jewelry he wears) was to essentially solidify the fact that he was no longer going to follow Odin’s law. Of course, there was no PROPER ‘apparel’ law, but this was a stepping stone in his goal to bring forth Ragnarok. The change happened after Hel was maimed and sent away; all Loki did was watch and do nothing (not that he really COULD when he’d be outnumbered) whilst his daughter, his very first child, was pretty much murdered. That scene set him on the path to Ragnarok; he even fled from Asgard for a time.
The reason he wears the golden bangles that range from his elbow to his wrist, however, is to cover up the scars that were left when he broke free of the chains he was bound to after Odin sent Thor after him for Baldr’s death & the birth of Hel. When he broke free of the chains, he tore some of his skin off of his arms and although he COULD heal them, he ensured he was left with a reminder of what Odin did to him and even to Hel. THAT was the defining moment for Ragnarok. THAT was when he knew he had to get revenge.











