Kendall has always had a fantastic singing voice. If you can find a copy, get James Byrd's Crimes of Virtuosity album. It featured "Kendall Tory" on vocals. That's Kendall Bechtel. Nice little gem in the power metal meets guitar virtuoso genre.
As for Fifth Angel, I don't think the first two sound alike in style (one was metal, the other was sleek hard rock). But listen to the rhythm guitars, and the style used throughout. All that is Ed's writing. And you'll hear the similarity.
As for The Third Secret, it misses that rhythm guitar style quite a bit. And while I think Kendall did a fantastic job on the guitars, he's just not the rhythm player that Ed is. His leads are incredible though.