Dry brushing could indeed pose a problem. I usually attach the magnetised arms to something like a file and use that as a handle. But I don't use dry brushing, so that probably won't help you much. I do however believe that it should be possible to focus on one part of the arm for drybrushing while holding the arm at the other end and repeating it with the opposite ends after it has completely dried. I don't think there's much in the way of an alternative, really.
Kabal of the eternal Pain- my Army log