Hello- sorry it took so long but I was out bush whacking- anyways as far as BA goes, I think the DO had it figured out. Y`know, the BA would really not be soooo hard to suss out if all it took was to stand around in a group and the ones that look old are the baddies. I figure any oaths sworn on a binder have the same effect regardless of the specifics. Also, I do believe that at some point on one of the posts here, we have gone into guessing the nature of the various oaths the BA must have taken. Vows to kill baby kittens, have mayo on their hamburgers, stepping on cracks in the sidewalks, and the like...
Hi there! It's kind of hidden in the detail, but here's how it works. Only a channeler who has sworn three (or possibly more) oaths on an Oath Rod will acquire the ageless look; as you say, an AS who is stilled (or probably burnt out, though we haven't seen that "on screen") will look young again. Oddly enough, she doesn't look just like she did when she actually was young, though. Not sure what causes that. But for the BA, when they join up the Oath Rod is used first to release them from the Three Oaths and then to swear three new oaths. So they don't lose the ageless look because they are still bound to three - just a different three. We don't know what they are, except the one that says not to betray the DO "to the hour of my death" or something to that effect. Note that the ageless look is not lost instantaneously, but over the course of a few days; RJ said Siuan and Leane changed faster than normal because of the trauma inflicted on them after their stilling. So when a BA is loosed and resworn, there's not time in between for her looks to change to any noticeable degree.
Hope that made sense - editing in the shoutbox isn't quite as easy as the comment box! P.S. Congrats on "going gray!" ;)