A good metallic bag catches the light and moves on, a cheap one catches the light and holds you hostage for the rest of the evening, flashing under every ceiling bulb like it's trying to signal a passing ship. You can spot the difference across a room before you've even clocked the shape of the thing.
The easiest metallics to live with aren't the loud golds and silvers you picture first, they're the muted ones, pewter, gunmetal, a soft bronze that reads almost like a dark neutral until the sun hits it. Those wear like a plain bag with a secret, which is exactly what you want from something that's meant to go everywhere, not announce itself at the door. True silver and gold have their place but they ask more of an outfit, and I learned that the hard way with a bag so bright it made my navy coat look like it was apologising for itself.
Where a metallic bag actually proves its worth is against things you already own and weren't expecting to pair it with. Plain jeans and a white shirt, a grey jumper, a black dress you've had for years and stopped noticing, all of it gets a small lift without you having to think. It sits happily with denim, with tailoring, with the sort of midweek outfit that has nothing special going on until the bag does its bit. If you're starting with none, go for a mid sized shoulder bag in pewter or a soft gold rather than a clutch, because a clutch only comes out a handful of times a year and a shoulder bag earns its spot by actually getting used on ordinary days, running errands, meeting someone for coffee, the lot.
How it ages depends almost entirely on the finish, and this is where the high street tends to let you down. A laminated or foiled surface will crack and flake at the corners within a year, usually right where your hand grips it, which is its way of telling you it was never metal underneath at all. A proper metallic leather or a well made synthetic with the colour worked right through holds up far better, scuffing gently rather than peeling, and actually looks more interesting with a few years on it. Keep it out of direct sun when you're not using it, wipe off any marks straightaway rather than letting them sit, and don't shove it to the bottom of a drawer under heavier bags, the creasing shows more on metallics than on anything plain.
A decent metallic bag doesn't dress anything up so much as it quietly suggests you made more effort than you did.