Dev here. If you’re referring to a duster you’ve got IRL and it doesn’t cover your legs effectively, it might be closer to DDA’s concept of a trenchcoat instead. About the only difference in-game is that the duster covers legs.
(Mine IRL is decidedly a trenchcoat.)
This was a point of some friendly contention for a while before we merged in the dusters, so confusion is understandable.