I might be hijacking this thread a little, but how would you apply this to Gil-Galad, since he is taking the card into hand rather than playing it?
All that "
Skirmish or Regroup:" says is that the card has two actions written on it, one a skirmish action and one a regroup action. So anything that would pull a skirmish action or a regroup action from the draw deck or discard pile can pull
Sword Wall. Likewise, if there were some condition that said "You may play regroup events during the maneuver phase," you'd be able to play
Sword Wall then too. It isn't a skirmish action
and a regroup action, it's a skirmish action
or a regroup action: you get to pick which.