dressed to kill 

Dressed, as in, such a fashion to look impressive enough, for someone to compliment someone (usually a Man compliments the lady, on this situation) "if looks could kill, you'd be a weapon of mass destruction"

wow, Celeste, even though this is a semi-formal, you're dressed to kill, babe!

dressed to kill by Allen June 17, 2006

Dressed to kill 

In the early days of organized crime, the most deadly, viscous, and criminal mobsters used to dress in very nice clothes (suits) for uniformity and intimidation purposes. Of course being the mob gangsters they were, they killed a lot of people in their everyday attire of suits and ties.

Example 1

Jim: How do you like my tuxedo for prom tonight??

Jim's father: Well, I'd say that you're dressed to kill son....

Example 2

Jerry: Man, did you see those 2 hitmen in Breaking Bad?

Jeffery: Yeah I did man, they were dressed to kill, yo!!

Dressed to kill by Larry Berkshire March 2, 2018