Keep your EDC to a minimum and distributed. Think about pocket carry and the gear that you'd want to assist in getting back to your cabin/stateroom which is where you'll have a Go-Bag right next to your life-jacket/PFD. The Go-Bag can carry a lot of good gear to aid in rescue but needs to be small enough to not impede moving through crowded passageways and into a lifeboat/raft.

I'm thinking that EDC is a very capable but small flashlight and wallet. It's very rare that a cruise ship sinks, but they have power outages more often than they'd like to admit. It's dark inside a ship when the lights go out. I'd consider a 1xAAA or one of the 4Sevens' mini 1xAA or 1x123A lights with a wrist lanyard. That's the entire EDC for me. Learn the ship's layout so you don't need a map, otherwise carry a map.

All the other good ideas (including passports, cash, important tickets et al) in this thread would be put into the Go-Bag. Part of the Go-Bag might be a set of clothes chosen specifically for abandoning ship; you don't want to make these decisions on the fly, things will be forgotten/lost in the rush. Pre-plan the details . . . and be prepared to flex when Plan A doesn't work. The most important item in EDC is your head which is where you'll find Plan B.