I dunno if you've gotten confirmation on this or not, but I can personally confirm the drop of a Kevlar Cheongsam from a Killer Closet, in the factory north of Canabelle, in the dorm-like area where you find the Saratoga Suit.
I wasn't sure how to prove it, but I did think to nab a screenshot from the end of the battle.
Also, the Suicide Sword (drop from the Army Zombie) has a chance of an instant kill against most organic enemies, even bosses. The text is formatted wrong, but it brings up a message about the enemy's breath stopping.
It worked against Gomez and Salmonella HQ. I don't have proof of this, though, but I can get it if you want.
Look, for the last time: Kirby has explained it over and over! http://i279.photobucket.com/albums/kk138/Schesparn/11911255317531.gif