While "Welcome Home" has heavy and metallic passages, particularly towards the end, I wouldn't call it a song that defines metal.
This would imply that metal has to have acoustic passages, be slow, and have its main licks stolen from someone else's songs
As for Black Sabbath - are you including "The Wizard" among "Anything"?
That track sounds a lot like early Jethro Tull to me, so by implication, you're saying that Tull are the epitome of metal. Shurely shome mishtake?
update: Hmm... the post I replied to has gone mysteriously AWOL.
Dio was the other consideration made - and I didn't reply immediately because
a) I don't know all the band's albums
b) Dio (the band) are a bit of a conundrum as far as the definition of metal is concerned;
In many ways, both "Holy Diver" and "The Last In Line" are a brilliant and concise summary of what Heavy Metal was all about in the pre-thrash 1980s - not bad for an American band.
On the other hand, despite the technical proficiency, impeccable song structuring, smokin' riffs and all-out heavy metal rock and rollness of the band, who were awesome live, the music smacked heavily of commercial orientation, what with stupid songs like "Mystery", and Dio the band were more like a commercial machine than a "proper" metal band from dahn the pub, as we say in England. They'd pretty much sold out from the word go - but hey, most of the music was great.
I didn't like "Sacred Heart" or "Dream Evil" at the time - but at that time I was almost completely absorbed in thrash, being in a thrash band myself, and found the music too samey and old.
If you think about it, this is a bit hypocritical of me, given that Ronnie James Dio only ever sang about Rainbows, Wizards and Stars in the 30 years or so after he introduced Elf to Ritchie Blackmore. With a voice like that, though, he could repeat himself ad nauseam and theoretically at least, no-one should care what the words are, as long as he doesn't stop singing!
Some of the stuff on "Last In Line" is particularly worth revisiting - the range of different material, from the adrenaline fuelled power metal of "I Speed At Night" to the pulsing Prog Metal of "Egypt" to the evil MTV-pleasing "Mystery", there really is something for everyone here;
For two years, I'd agree - Dio
did define metal, and for this and the stuff he did with Rainbow and Black Sabbath (even though it's exactly the same), he gets a triple entry into the metal Hall of Fame.
Now where's the Devil Horns emoticon when you need it?