"I had simply believed in myself..."

This is his "coming out" outfit.

But also... The angst of Viktor being seen as a traitor for assimilating to Piltover life, leaving Zaun for the glitzy high life, Zaun seeing nearly none of the hextech advancements for possibly years after it's finalized and made and Viktor having a hard time justifying any of it to them. He gets protection from enforcers, who actively harass and kill Zaunites at any given opportunity.

And Viktor still loving his city even if it could never love him, accept him, understand him. He feels it's suffering, grows impatient to help them all, puts Zaun and it's people well before him and his happiness.

I Think he looks good in it, I just don't think he likes it.