The last section is the fleur de lis, the symbol of France, and often appears on British coats of arms to emphasize the desire to control France -- although, the few times Britain HAS controlled France, it represents that actual control.
The motto appears to be similar to that used by the Order of the Garter, meaning "Shame to him to thinks ill of it." -- but much of the language appears to be missing. It would read honi soit qui mal y pense"