I think people who really get stuck into Arc should be called ArcTicks.
But seriously: I read "arcist" with a "ss" sound instead of a "k" sound for the "c", and it sounded rude. Mind you, that's with an Australian accent.
Rummaging through /usr/share/dict/words: the Arc Forum can be the Arcade, and its regular posters Arcadians, with perhaps the top poster (in quality, not quantity) given the title Archimedes; backwards compatibility issues are archaisms; PG is the Archangel, or perhaps the Architect (Lisp is the red pill!); Arc programmers in general are Archaeologists; the growing collection of Arc websites form the Archipelago; type safety is discussed in a forum called the Archetype; old posts go into the Archive... The potential is endless!