An archeology grad student who speaks Arabic indicated that the final 's' is slightly sibilant, and the closest English pronunciation would be with a subtle 'h' tacked on. If one were to err, 'sh' would be closer than a plain 's'. Somewhere between 'raze' and 'raish'. But not 'razz'.

Also, IIRC the animated series used the same slight 'sh' pronunciation, but that could have just been David Warner hamming it up with that wacky accent of his. :)