I think the new one is better in terms of recognizing the activated state. A similar change could have been made to the old icon, to prevent people having to get used to something somewhat different, but eh.
I also think that the old armlet looked "cool", but I can dig the change. It looks nice. I couldn't say the same about the Vanguard icon—that's really the only change that I think needs a revert or a rework.