>>7508173been a while since I watched the show, but that was like only a few scenes where she flairs out the coat like that for dramatic effect. IIRC she usually just whipped a derringer out from under the concealment of her coat to take people who falsely assumed her unarmed by surprise.
here is an image of the old toy. The creator of the manga was such a HUGE toy nerd that he was very closely involved with the designs of the toys so this is pretty much how he envisioned her harness to look like underneath all the layers she wore to conceal them. wether or not it's feasible is a different story, but stuff like the pic earlier were pretty much outright anime dramatic physics in work and she usually just grabbed them while in a more neutral stance