I'm in the same boat -- I know Aitan Anzelm had supernatural abilities (showing
everybody that he was not just "a regular fellow who happens to have pointy ears,") as did the other angels in Tom's world, but I don't recall exactly what they could do, or what hisAitan's own field of expertise was among his kind!
Yes, I remembered that the angel thing was all a scam. It was established right away in the text that, by the time this story was taking place, virtually all
of the humans, and implicitly a great many of the "angels," were, in fact, firm believers in the validity of the term "angel" for this nonhuman race. Which turned out to be self-serving religious propaganda invented by the original batch of elves who had taken refuge on Earth. Tom's master, as I recall, was definitely one of those true believers. After all, why shouldn't he believe what his elders had been telling him for all of his life? But, as you say, they were simply elves whose ancestors had fled to Earth from some other world.
On the other hand, the good news for you is that this was, in fact, always intended as the first installment of a trilogy, and the other two books were published afterwards. (Apparently spaced about a year apart -- 1996, 1997, 19971998.) According to ISFDB, the Elven Ways trilogy consists of: