I doubt that they will let you bring the mace. Since everyone is in such closed quarters, it could do a lot of damage if it gets sprayed.
As far as the key, I bought a keychain key to the Magic Kingdom in WDW before we left on the cruise. It's bigger than the Haunted Mansion key and there were no problems, so that should be fine.
If you're really concerned, you can probably call the Disney and ask them - I'm sure they get those calls all the time.