Randy Rhoads was a guitar god before the term was even around.  He blended classical guitar into this heavy riff oriented music Ozzy was making.  Who knows what would've become of Ozzy if Randy hadn't joined his post Sabbath band.  There's no denying the magic that happened when both of them got on stage together.

A signature sound is something every guitarist strives for.  A signature playing style is better.  Signature guitar is pretty ok too.  If you're interested in what when into making his classic "flying v" guitars...Premiere Guitar put together a pretty cool article.