I'm pretty sure he is
Stanley was fairly smug that Ansom wasn't attuned, and seems to be able to do a variety of tricks with the Hammer. Unlike Ansom and his pliers, which he could only use as a weapon (that we saw, anyway).
I think this is one of those "the author thought it was so obvious from art and implications that it's never explicitly stated" kinda things.
Originally Posted by Randel
How about the fact that humans can apparently breed with anything on two legs (or even four legs if you count dragons)?
Human: Hey elf, you look like a girl.
Elf: To a human, everything must look like a girl.
Elf: Half-orcs, half-ogres...
Human: ... shut up.
Dwarf: Half-dragons, half-kobolds.
Human: I said shut up!