The characteristics fall into many areas and going down the elemental route is fraught with danger - or at least red herrings - as the Wikipedia article illustrates, albeit unintentionally.
I've set up the "Bands that define metal" thread as a kind of net to try and trap the characteristics. This might take some time, of course - but I'm in no hurry
Obviously, metal is more than Sabbath, Motorhead, Dio and Maiden - there are more modern bands to consider too.
Unless there's compelling evidence to the contrary, I'd suggest Metallica as the ultimate metal defining band - and not because they're my favourites, but because they released 5 genre-redefining albums before going completely crap.