Now that's just silly. Why would anyone wear evening dress as an assassin ? Cumbersome; as noticeable as wearing all black; nowhere to hide the gun before or after; can't run, and generally sticking out like a cardinal on a dance club floor.
For blending in, and acutally all too common from alot of drama movies i've seen. You kill someone at the festival/dance or whatever. Being a buxom hottie only makes it easier. You get your target and just act slutty and once you 2 are all alone, just kill him there and then walk away.
If anything, You don't even need to bring your own murder weapon as you can easily just pick up a knife or some trophy on the desk to kill your target anyway. But if you must bring a weapon, usually the ol "watch with a choke string" or "knife hidden on strap thiegh" works.
